Absorbent articles with biocompostable properties

ABSTRACT

Disclosed is an absorbent article with biocompostable properties, such as a baby diaper or adult incontinence product. Particularly, the present invention is directed to a biocompostable absorbent sanitary article including a blend of synthetic and bio-based superabsorbent polymers with a high degree of biocompostability. The sanitary article comprises, in one embodiment, at least a top layer, a back layer, and absorbent core, wherein the absorbent core includes a superabsorbent polymer, and wherein at least the superabsorbent polymer is biocompostable.

CROSS REFERENCE TO RELATED APPLICATIONS

This application relates to and claims priority from the followingapplications. This application is a continuation of U.S. applicationSer. No. 17/039,101, filed Sep. 30, 2020, which is acontinuation-in-part of U.S. application Ser. No. 16/592,948, filed Oct.4, 2019, which is a continuation-in-part of U.S. application Ser. No.14/728,240, filed Jun. 2, 2015, which claims the benefit of U.S.Provisional Patent Application No. 62/006,317, filed Jun. 2, 2014. Eachof the above-mentioned applications is incorporated herein by referencein its entirety.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention generally relates to sanitary articles withbiocompostable properties, including disposable baby diapers, adultincontinence products, and menstrual pads. Particularly, the presentinvention relates to sanitary articles with elements that include highbioderived content, including absorbent cores with superabsorbentproperties and high biocompatibility.

2. Description of the Prior Art

Sanitary absorbent articles are used for a variety of hygienic purposes,including infant and adult incontinence and menstruation. Articles aretraditionally constructed with a variety of layers that aid in thedistribution and absorption of fluids while providing comfort to a user.Often, the hygienic articles are constructed with layers and absorbentmaterials, such as superabsorbent polymers (SAPs), that aresynthetically derived, are non-biodegradable, and arenon-biocompostable.

Consumers have expressed an increased desire for biodegradability and/orbiocompostability in absorbent sanitary articles. As such, biopolymersand bio-derived polymers for integration in the absorbent articles havebeen examined for their absorbency properties, including naturallyoccurring materials and their derivatives, such as starches, celluloses,and polysaccharides. However, these biopolymers are often more difficultto synthesize, more expensive to make, and have inferior absorptionproperties relative to traditional, non-biocompostable materials, suchas polyacrylates.

Examples of relevant prior art documents include the following:

U.S. Patent Publication No. 20180153746 for “Biodegradable sanitaryarticles with higher biobased content” by inventor Sookraj, filed Dec.6, 2016, and published Jun. 7, 2018, is directed to sanitary articlessuch as disposable diapers, adult incontinent pads, feminine hygieneproducts, and sanitary napkins comprised of biodegradable polymers withhigher biobased content. The sanitary articles include a topsheet, anabsorbent core, and a backsheet. The topsheet is comprised ofbiodegradable polyester polyol polymer foam which may be configured towick liquid away from a wearer's body and may be impregnated withsuperabsorbent polymer. The absorbent core may be comprised ofsuperabsorbent polymer including a cross-linked and/or partiallyneutralized polyacrylic acid polymer, cross-linked polyacrylic acids orcross-linked starch-acrylic acid graft polymers. The backsheet may becomprised of poly-lactone polymers having generally hydrophobiccharacteristics. In preferred embodiments, the polymeric materialscomprising the topsheet, absorbent core, and backsheet are formed fromraw materials with high biobased content.

U.S. Patent Publication No. 20170021051 for “Biodegradable AbsorbentArticles” by inventor Richards, et al., filed Jul. 15, 2016, andpublished Jan. 26, 2017, is directed to a biodegradable, disposableabsorbent article, such as a diaper, having a non-woven inner layer ofnatural fibers and a non-woven outer layer of natural fibers and atreatment applied to at least one surface thereof. The treatmentincludes at least one compound selected from the group consisting ofwaxes, urethanes, silicones, fluorocarbons, and non-fluorochemicalrepellents. The absorbent article has a core of natural fibers orfibrous material, and optionally polyacrylate superabsorbent particles,positioned between the inner layer and the outer layer. The article maycontain polylactic acid films between the layers.

U.S. Patent Publication No. 20170224540 for “Biodegradable, biobaseddiaper” by inventors Li, et al., filed Aug. 8, 2015, and published Aug.10, 2017, for a disposable diaper that is biobased and/or biodegradable.The diaper is either made of wholly or partially renewable resources, atthe same time can decompose in a compost site, and biodegrade in aconventional landfill as well as in marine conditions such as fresh,brackish or salt water.

WIPO Publication No. WO2012064741 for “Method for the production ofsubstituted polysaccharides via reactive extrusion” by inventors Hanna,et al., filed Nov. 8, 2011 and published May 18, 2012, is directed to areactive extrusion process for the production of substitutedpolysaccharides, in particular, cellulose acetate, starch acetate,carboxymethyl cellulose, and carboxymethyl starch.

U.S. Pat. No. 8,710,212 for “Starch networks as absorbent orsuperabsorbent materials and their preparation by extrusion” byinventors Thibodeau, et al., filed Mar. 26, 2004 and issued Apr. 29,2014, is directed to an absorbent material consisting of a molecularnetwork of starch molecules, the starch molecules comprising anamylopectin content of at least 90% (w/w). The molecular network caneither be comprised of self-entangled starches or cross-linked starches.

WIPO Publication No. WO2013096891 for “Algal thermoplastics, thermosets,paper, adsorbants and absorbants” by inventors Harlin, et al., filedDec. 21, 2012 and published Jun. 27, 2013, is directed to biomass-basedmaterials and valuable uses of microalgal biomass including: (i)acetylation of microalgal biomass to produce a material useful in theproduction of thermoplastics; (ii) use of triglyceride containingmicroalgal biomass for production of thermoplastics; (iii) combinationof microalgal biomass and at least one type of plant polymer to producea material useful in the production of thermoplastics; (iv) anionizationof microalgal biomass to form a water absorbant material; (v)cationization of microalgal biomass, and optional flocculation, to forma water absorbant material; (vi) crosslinking of anionized microalgalbiomass; (vii) carbonization of microalgal biomass; and (viii) use ofmicroalgal biomass in the making of paper.

WIPO Publication No. WO2013180643 for “A fiber-based substrate providedwith a coating based on a biopolymer material and a method of producingit” by inventors Johansson, et al., filed May 31, 2013 and publishedDec. 5, 2013, is directed to a coated product, comprising a substrateand a coating layer, wherein said substrate is in shape of a web, sheetor tray of fiber-based material such as paper or paperboard, and whereinsaid coating layer forms a barrier on the substrate and mainly containsbiopolymer material cross-linked by a cross-linking agent, wherein thecross-linking agent is citric acid in a range of 14-50 pph, and thebiopolymer material is diesterified and hydrolyzed to an extent of lessthan 80%, preferably less than 50% and most preferred less than 30%.

WIPO Publication No. WO2008022127 for “Process for producing biopolymernanoparticles” by inventors Wildi, et al., filed Aug. 14, 2007 andpublished Feb. 21, 2008, is directed to a process for producing abiopolymer nanoparticles product. In this process, biopolymer feedstockand a plasticizer are fed to a feed zone of an extruder having a screwconfiguration in which the feedstock is processed using shear forces inthe extruder, and a crosslinking agent is added to the extruderdownstream of the feed zone. The biopolymer feedstock and plasticizerare preferably added separately to the feed zone. The screwconfiguration may include two or more steam seal sections. Shear forcesin a first section of the extruder may be greater than shear forces inan adjacent second section of the extruder downstream of the firstsection. In a post reaction section located after a point in which thecrosslinking reaction has been completed, water may be added to improvedie performance.

U.S. Pat. No. 5,599,916 for “Chitosan salts having improved absorbentproperties and process for the preparation thereof” by inventorsDutkiewicz, et al., filed Dec. 22, 1994 and issued Feb. 4, 1997, isdirected to a method for producing a water-swellable, water-insolublechitosan salt having improved absorption properties. The method involvesforming a mixture of a chitosan, water, an acid, and, optionally, acrosslinking agent, recovering the formed chitosan salt from the mixtureand, optionally, treating said recovered chitosan salt with heat orunder humid conditions.

U.S. Pat. No. 4,590,081 for “Method of manufacturing foamed foodstuff”by inventors Sawada, et al., filed Mar. 1, 1984 and issued May 20, 1986,is directed to a method of manufacturing a foamed foodstuff by insertingpowdered and granular ingredients for a foodstuff into an extruder whichis provided with two screws which mesh with each other and rotated athigh speed in the same direction, mixing and heating the ingredients ina preheating zone, adding a predetermined quantity of a liquid to themixed ingredients in a liquid-addition zone, kneading the moistenedingredients in a kneading zone, transforming the starch in theingredients into alpha starch in an alpha formation zone, and thenextruding the ingredients from the extruder.

WIPO Publication No. WO2002074814 for “Batch cookable modified highamylose starches and their use in paper sizing applications” byinventors Billmers, et al., filed Mar. 16, 2001 and published Sep. 26,2002, is directed to pregelatinized modified, high amylose starches thatare batch cookable to a uniform, substantially particle-free dispersionat atmospheric pressures and the process of preparing such starches inan extruder. Such pregelatinized, modified, high amylose starches areuseful in a variety of applications without the need for jet cooking. Inaddition, such starches are readily dispersible at high solids toprovide uniform formulations and are substantially non-retrograded.Further, such starches provide improved surface sizing agents which useresults in the preparation of paper which is characterized by improvedwater resistance, reduced porosity, and other size properties.

U.S. Pat. No. 8,383,573 for “Dual character biopolymer useful incleaning products” by inventors Dupont, et al., filed Nov. 18, 2009 andissued Feb. 26, 2013, is directed to new cleaning compositions includingnovel amphoteric dispersant polymers containing anionic and nitrogencontaining substitution are disclosed. In particular, cleaningcompositions containing modified polysaccharides having anionic andnitrogen containing substitution and methods of forming the same aredisclosed.

U.S. Publication No. 20120121519 for “Natural polymeric emulsifiers andmethod for use” by inventors Thomaides, et al., filed Nov. 7, 2011 andpublished May 17, 2012, is directed to polymeric emulsifiers includingpolysaccharides modified with at least one cross-linking reagent andwith from about 1 mol % to about 10 mol % of at least one ionic reagent,methods for preparing the same, and emulsions including the polymericemulsifiers.

SUMMARY OF INVENTION

The present invention relates to modified biopolymers, includingcharge-modified biopolymers, crosslinked biopolymers, and/orcrosslinked, charge-modified biopolymers. In particular, the presentinvention relates to modified biopolymers used as superabsorbentpolymers. Methods of producing and using a modified biopolymer of thepresent invention are also provided.

These and other aspects of the present invention will become apparent tothose skilled in the art after a reading of the following description ofthe preferred embodiment when considered with the drawings, as theysupport the claimed invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic of a heterogeneous phase reaction.

FIG. 1B is a schematic of a homogeneous phase reaction.

FIG. 2 illustrates a parallel twin screw extruder with multipleinjection and reaction zones according to embodiments of the presentinvention.

FIG. 3 illustrates Fourier-Transform Infrared Spectroscopy (FTIR)spectra for unmodified hemicellulose and charge-modified hemicelluloseaccording to embodiments of the present invention.

FIG. 4 illustrates FTIR spectra for unmodified pectin andcharge-modified pectin according to embodiments of the presentinvention.

FIG. 5 illustrates FTIR spectra for unmodified soy protein andcharge-modified soy protein according to embodiments of the presentinvention.

FIG. 6A illustrates exemplary “low shear” screw configurations accordingto one embodiment of the present invention. FIG. 6B illustratesexemplary “medium shear” screw configurations according to oneembodiment of the present invention. FIG. 6C illustrates exemplary “highshear” screw configurations according to one embodiment of the presentinvention.

FIG. 7A shows a Scanning Electron Microscope (SEM) image of acommercially available cationic starch at 33× magnification.

FIG. 7B shows a SEM image of the commercially available cationic starchat 1000× magnification.

FIG. 7C shows a SEM image of an Energy Dispersive X-ray Spectrometry(EDS) chlorine map of the commercially available cationic starch.

FIG. 7D shows a SEM image of a cationic starch prepared according tomethods of the present invention at 33× magnification.

FIG. 7E shows a SEM image of the cationic starch prepared according tomethods of the present invention at 1000× magnification.

FIG. 7F shows a SEM image of an EDS chlorine map of the cationic starchprepared according to methods of the present invention.

FIG. 8 illustrates FTIR spectrum for unmodified industrial grade cornstarch.

FIG. 9 illustrates FTIR spectrum for charge-modified starch according toone embodiment of the present invention.

FIG. 10 is a chart illustrating the percent degradation of two modifiedcorn starch based biopolymers compared to analytical grade cellulose andpolyethylene.

FIG. 11A is a pair of graphs illustrating acquisition under load andrewet absorbency for absorbent core constructs made with blends ofsuperabsorbent polymers according to one embodiment of the presentinvention.

FIG. 11B is a pair of graphs illustrating a comparison of salineacquisition for absorbent core constructs made with blends ofsuperabsorbent polymers according to one embodiment of the presentinvention.

FIG. 12 illustrates layers of a sanitary absorbent article, including atopsheet, acquisition distribution layer, absorbent core, and backsheetaccording to one embodiment of the present invention.

FIG. 13 illustrates a baby diaper with biocompostable, absorbentproperties according to one embodiment of the present invention.

FIG. 14 illustrates a menstrual pad with biocompostable, absorbentproperties according to one embodiment of the present invention.

FIG. 15 illustrates an incontinence product with biocompostable,absorbent properties according to one embodiment of the presentinvention.

FIG. 16 illustrates a chart showing the Capacity/Core Wt and FSC vsPercent SAP A w/w in Blends with commercial non-biobased SAP.

DETAILED DESCRIPTION

The present invention is generally directed to sanitary articles withbiocompostable elements. In general, this includes articles with aseries of layers, including a top layer, a back layer, and an absorbentcore, wherein the absorbent core preferably integrates modifiedbiopolymers, including charge-modified biopolymers, crosslinkedbiopolymers, and/or crosslinked, charge-modified biopolymers. Inparticular, the invention incorporates modified biopolymers used assuperabsorbent polymers. Particularly, the superabsorbent polymerincludes a high degree of bioderived content and is preferablybiocompostable. Methods of producing and using a modified biopolymer ofthe present invention are also provided.

Superabsorbent polymers are crosslinked hydrophilic polymers that absorband retain large amounts of liquids. In general, superabsorbent polymersare able to absorb and retain at least 10 times their weight of a 0.9%NaCl solution, also referred to as a “saline solution” throughout thepresent application. Due to their ability to absorb liquids,superabsorbent polymers are often used in absorbent articles (e.g.,diapers, incontinence products, feminine hygiene products, wounddressings).

Most superabsorbent polymers are formed of polyacrylates, which areformed from monomers (e.g., acrylic acid, acrylamide) obtained fromnon-renewable sources. However, polyacrylates are generally notbiodegradable. Additionally, polyacrylates often contain some residualmonomers, which may be toxic or cause allergic contact dermatitis.

In one embodiment, the present invention is directed to a biocompostableabsorbent sanitary article, including a fluid-permeable top layer, afluid-resistant back layer, and an absorbent core, wherein the absorbentcore includes a superabsorbent polymer (SAP), wherein the SAP includes amodified starch-based biopolymer, wherein the SAP is biocompostable, andwherein the biobased carbon content of the SAP is at least approximately50%. In one embodiment, the SAP does not include a synthetic polymer. Inanother embodiment, the biobased carbon content of the SAP is betweenapproximately 60% and approximately 95%. In yet another embodiment, thebiobased carbon content of the SAP is between approximately 80% andapproximately 90%. In yet another embodiment, the biobased carboncontent of the SAP is between approximately 84% and approximately 90%.In another embodiment, the biocompostable absorbent sanitary articleincludes an acquisition distribution layer (ADL), wherein the ADL isoperable to wick and distribute fluid from the fluid-permeable top layerto the absorbent core. In another embodiment, the SAP is furtherintegrated into the fluid-permeable top layer. In another embodiment,the fluid-permeable top layer, the fluid-resistant back layer, and/orthe absorbent core are biocompostable. In another embodiment, theamylose content of the modified starch-based biopolymer is less thanabout 85% w/w. In another embodiment, the SAP has a centrifuge retentioncapacity (CRC) of at least about 12 g/g or an absorbency under load(AUL) at 0.7 psi of at least about 8 g/g in a saline solution. Inanother embodiment, the SAP exhibits no cytotoxicity and is not a dermalirritant. In another embodiment, the modified starch-based biopolymer iscrosslinked using succinic acid, adipic acid, citric acid, magnesiumacetate, aluminum lactate, aluminum acetate, aluminum hydroxide,aluminum chloride, zinc chloride, malonic acid, and/or glycerol. Inanother embodiment, the SAP exhibits over 40% degradation in 60 days and60% degradation in 90 days relative to an analytical grade cellulosecontrol. In another embodiment, at least about 95% of the particle sizesof the SAP are between about 150 micrometers (about 0.00394 inches) andabout 850 micrometers (about 0.0256 inches). In another embodiment, thearticle is one of: a baby diaper, an adult incontinence product, or amenstrual pad. In another embodiment, the biobased carbon content of theSAP is at least about 80%.

In another embodiment, the present invention is directed to abiocompostable absorbent sanitary article including a fluid-permeabletop layer, a fluid-resistant back layer, and an absorbent core, whereinthe absorbent core includes a superabsorbent polymer (SAP) and absorbentfiber, wherein the SAP includes a modified biopolymer, and wherein theamylose content of the modified biopolymer is less than about 80% w/w.In one embodiment, the article includes at least an intermediate layer,wherein the intermediate layer does not include the SAP. In anotherembodiment, the SAP is biocompostable such that the SAP is operable toexhibit at least 90% degradation within 180 days when compared toanalytical grade cellulose in a test directed by ASTM D5338 or anequivalent biodegradation test. In another embodiment, the articleincludes at least one adhesive between layers of the biocompostableabsorbent sanitary article, and/or an external adhesive, wherein the atleast one adhesive and/or the external adhesive are biocompostable suchthat the at least one adhesive and/or the external adhesive is operableto exhibit at least 90% degradation within 180 days relative to ananalytical grade cellulose control. In another embodiment, the articleis constructed from at least 75% biobased carbon content. In anotherembodiment, the modified biopolymer is crosslinked using succinic acid,adipic acid, citric acid, magnesium acetate, aluminum lactate, aluminumacetate, aluminum hydroxide, aluminum chloride, zinc chloride, malonicacid, and/or glycerol. In another embodiment, the absorbent core isfolded at least once such that the absorbent core forms a centrallongitudinal channel and/or such that the absorbent core forms two ormore layers. In another embodiment, the modified biopolymer includes amodified starch-based biopolymer made from corn starch, potato starch,pea starch, and/or tapioca starch. In another embodiment, ethanol is notused in a charge modification step of an extrusion process in making theSAP. In another embodiment, biobased carbon content of the SAP is atleast 80%. In another embodiment, the SAP has a free swell capacity(FSC) of at least 25 g/g in a 0.9% saline solution, a centrifugeretention capacity (CRC) of at least about 16 g/g in a 0.9% salinesolution, and an absorbency under load (AUL) at 0.7 psi of at leastabout 6 g/g in a 0.9% saline solution.

Another embodiment of the present invention is directed to abiocompostable absorbent sanitary article, including a fluid-permeabletopsheet, a fluid-resistant backsheet, an acquisition distributionlayer, and an absorbent core, wherein the absorbent core includes atleast cellulose fluff pulp and an integrated superabsorbent polymer(SAP), and wherein the SAP includes a modified biopolymer, and whereinthe SAP is biocompostable such that the SAP is operable to exhibit atleast 90% degradation within 180 days when compared to a cellulosecontrol.

Yet another embodiment of the present invention is directed to abiocompostable absorbent sanitary article, including a fluid-permeabletop layer, a fluid-resistant back layer, and a superabsorbent polymer(SAP), wherein the SAP includes a modified biopolymer, and wherein theSAP is biocompostable such that the SAP is operable to exhibit at least90% degradation within 180 days when compared to a cellulose control. Inone embodiment, the article includes an absorbent core without fluff. Inanother embodiment, the article includes an airlaid core. In anotherembodiment, the SAP has a free swell capacity (FSC) of at least about 13g/g in defibrinated sheep's blood or a centrifuge retention capacity(CRC) of at least about 12 g/g in defibrinated sheep's blood.

Referring now to the drawings in general, the illustrations are for thepurpose of describing one or more preferred embodiments of the inventionand are not intended to limit the invention thereto.

The present invention describes a modified biopolymer (e.g., acharge-modified biopolymer, a crosslinked biopolymer, and/or acrosslinked, charge-modified biopolymer), methods of producing themodified biopolymer, and articles containing the modified biopolymer. Inone embodiment, the crosslinked, charged-modified biopolymer is formedof one biopolymer that has been charge-modified and then crosslinked. Inanother embodiment, the crosslinked, charged-modified biopolymer isformed of at least two different biopolymers that are crosslinked and atleast one of the biopolymers has been charge-modified. In anotherembodiment, the at least two different biopolymers are crosslinked witheach other. In yet another embodiment, a crosslinked, charge-modifiedbiopolymer is formed of two different biopolymers that are crosslinkedand both of the biopolymers are charge-modified.

A “biopolymer” as used herein refers to a polymer that has at least onefree amine and/or hydroxyl group present on a majority of the monomericunits of the polymer and is a polymer produced by a living organism or aderivative thereof, or is a synthetic version of this polymer producedby abiotic chemical routes. In one embodiment, a free amine and/orhydroxyl group is present on each of the monomeric units of the polymerbackbone. Exemplary biopolymers include, but are not limited to,proteins and/or polysaccharides. As one of ordinary skill in the artwill understand, a biopolymer may be synthetically obtained (e.g.,through laboratory synthesis) and/or obtained and/or derived from nature(e.g., from a living or previously living organism). In one embodiment,the biopolymer is the same as a polymer found in nature (i.e., a nativebiopolymer) or is a derivative thereof. In another embodiment, thebiopolymer is a derivative of a polymer produced by a living organism,the derivative caused by the synthetic method used to obtain or isolatethe biopolymer from nature. In yet another embodiment, the biopolymer isa polymer produced by bacteria and/or microbes.

Further exemplary biopolymers include, but are not limited to, starches(including amylose and/or amylopectin), chitosans, hemicelluloses,lignins, celluloses, chitins, alginates, dextrans, pullanes,polyhydroxyalkanoates, fibrins, cyclodextrins, proteins (e.g., soyprotein), other polysaccharides (e.g., pectin), and/or polylactic acids.

A biopolymer used in a method of the present invention preferably has amoisture content of less than about 20% by weight. In one embodiment,the biopolymer has a moisture content of less than about 20%, less thanabout 15%, less than about 10%, or less than about 5% by weight. Inanother embodiment, the biopolymer has a moisture content in a range ofabout 5% to about 20% by weight or about 10% to about 15% by weight. Inyet another embodiment, a method of the present invention utilizes abiopolymer (e.g., starch) having a moisture content of less than about20% by weight. In one embodiment, the biopolymer is in powder form.

A biopolymer used in a method of the present invention preferably has amolecular weight of at least about 10,000 Daltons. In one embodiment,the biopolymer has a molecular weight of at least about 10,000; at leastabout 20,000; at least about 30,000; at least about 40,000, at leastabout 50,000; at least about 60,000; at least about 70,000; at leastabout 80,000; at least about 90,000; or at least about 100,000 Daltons.In a preferred embodiment, the biopolymer has a molecular weight of atleast about 50,000 Daltons. In another embodiment, the biopolymer has amolecular weight of about 100,000 Daltons to about 4,000,000 Daltons,about 500,000 Daltons to about 3,000,000 Daltons, or about 1,000,000Daltons to about 2,000,000 Daltons. In yet another embodiment, when onlyone biopolymer is used to prepare the modified biopolymer, thebiopolymer has a molecular weight of at least 50,000 Daltons. In stillanother embodiment, when two or more different biopolymers are used toprepare the modified biopolymer, at least one of the two or moredifferent biopolymers has a molecular weight of at least 10,000 Daltons(e.g., at least 20,000; at least 30,000; at least 40,000, at least50,000 Daltons). In one embodiment, the modified biopolymer is preparedusing a biopolymer having a molecular weight of at least 50,000 Daltonsoptionally with a second different biopolymer having a molecular weightof at least 10,000 Daltons. In another embodiment, the biopolymer ispolydisperse.

The present invention relates to the use of crosslinked, modifiedbiopolymers as superabsorbent materials or superabsorbent polymers. Theeffectiveness of superabsorbent polymers is typically measured usingFree Swell Capacity (FSC), Centrifuge Retention Capacity (CRC), and/orAbsorbance Under Load (AUL). FSC refers to the superabsorbent polymer'sability to swell, whereas CRC refers to the superabsorbent polymer'sability to retain absorbed liquid under force following swelling and AULrefers to the superabsorbent polymer's ability to swell under pressureduring swelling; AUL is generally directly related to “gel strength”.The AUL is critical to success in hygiene product constructions. Whenabsorbent particles have poor gel strength, these particles also havepoor permeability and the outer particles will swell too quickly,preventing fluid uptake of the innermost particles. This inhibits theabsorbent from swelling to its full potential and is known as gelblocking. Notably, the CRC and the AUL are generally inverselycorrelated, (i.e., a modified biopolymer with a higher CRC willtypically have a lower AUL than a modified biopolymer with a lower CRC).

In a preferred embodiment, the modified biopolymer (manufactured fromindustrial grade corn starch) has a Centrifuge Retention Capacity (CRC)of at least 15 g/g in a saline solution according to INDA/EDANA StandardNWSP 241.0.R2 (15) entitled “Polyacrylate SuperabsorbentPowders—Determination of the Fluid Retention Capacity in Saline Solutionby Gravimetric Measurement Following Centrifugation.” In anotherembodiment, the modified biopolymer has a CRC of at least 16 g/g or atleast 19 g/g in a saline solution according to this standard.Alternatively, the modified biopolymer has a FSC of between about 18 andabout 32 g/g and a CRC of between about 8 and about 19 g/g in a salinesolution. In another embodiment, the modified biopolymer has a FSC of atleast 25 g/g and a CRC of at least 17 g/g in a saline solution. In yetanother alternative, the modified biopolymer has a FSC between 28 g/gand 45 g/g and a CRC between 17 g/g/ and 30 g/g in a saline solution. Inanother embodiment, the modified biopolymer has a FSC of between about18 and about 24 g/g and a CRC of between about 13 and about 16 g/g indefibrinated sheep's blood. In yet another embodiment, the modifiedbiopolymer has a FSC of between about 21 and about 26 g/g and a CRC ofbetween about 15 and about 19 g/g in FDA menses simulant. In otheralternatives, the modified biopolymer has a FSC of between 18 g/g and 30g/g and a CRC of between 13 g/g and 20 g/g in defibrinated sheep's bloodand a FSC of between 21 g/g and 35 g/g and a CRC of between 15 g/g and25 g/g in FDA menses simulant.

The present invention is advantageously utilized in two absorbentformulations with distinct applications, namely a first type offormulations which includes internal crosslinking (referred to herein as“modified biopolymer 1”) and a second type of formulations whichincludes both internal crosslinking and surface crosslinking (referredto herein as “modified biopolymer 2”). Generally, modified biopolymer 1has higher FSC and CRC values than modified biopolymer 2, and isconsequently used in applications such as rheology modifiers. Modifiedbiopolymer 2 generally has higher AUL values, and is consequentlyutilized in hygiene applications such as baby diapers, adultincontinence products, and feminine hygiene products. In one embodiment,the modified biopolymer 1 formulation includes a FSC of about 40 g/g, aCRC of about 35 g/g, and an AUL of about 5 g/g in a saline solution.

While synthetic superabsorbent polymers such as polyacrylate typicallyhave a FSC of about 40 g/g, a CRC of about 35 g/g, and an AUL at 0.7 psiof about 15 g/g in 0.9% saline, the hygiene formulation of the presentinvention provides a biodegradable superabsorbent polymer with a CRCpreferably between about 20 g/g and about 30 g/g and an AUL preferablybetween about 10 g/g to about 15 g/g in a saline solution. In anotherembodiment, the modified biopolymer preferably has a FSC of at least 25g/g in a saline solution. In yet another embodiment, the presentinvention provides a biodegradable superabsorbent polymer with a CRC ofat least about 18 g/g and an AUL at 0.7 psi of at least about 8 g/g in asaline solution. FSC, CRC, and AUL values within these ranges areprovided in the examples below for specific formulations of modifiedbiopolymer 1 and modified biopolymer 2.

The modified biopolymer 1 and modified biopolymer 2 formulationspreferably utilize the same starch-based biopolymer. Notably, modifiedbiopolymer 1 formulations of the present invention include bulkcrosslinking (also referred to as “interior crosslinking”) and do notinclude significant amounts of surface crosslinking. Bulk crosslinkinginvolves crosslinkers forming covalent bonds between polymers and areassumed to be evenly distributed through the material. In contrast,modified biopolymer 2 formulations include both bulk crosslinking andsurface crosslinking. As used herein, the term “surface crosslinking”denotes chemical and/or physical interactions where polymers are nolonger freely soluble. Modified biopolymer 2 formulations generally haveincreased gel strength, but generally decreased retention compared tomodified biopolymer 1 material.

Advantageously, the modified biopolymers of the present invention aresuperabsorbent polymers and do not require addition of synthetics orintegration with synthetics such as polyacrylate to perform as asuperabsorbent polymer. Accordingly, the modified biopolymers of thepresent invention do not include acrylic-based polymers (polyacrylate,acrylamide, etc.) in one embodiment. In other words, the modifiedbiopolymers of the present invention are not graft polymers according toone embodiment of the present invention.

Alternatively, the present invention includes percentages of syntheticpolymers such as polyacrylate blended with the modified biopolymers ofthe present invention. By way of example and not limitation, syntheticpolymers such as polyacrylate are blended with modified biopolymer 2 ofthe present invention. Specifically, one blend includes 25% syntheticpolymer and 75% modified biopolymer 2 in one embodiment. In anotherembodiment, a blend includes 50% synthetic polymer and 50% modifiedbiopolymer 2. In other embodiments, ranges of synthetic superabsorbentpolymers included in blends with modified biopolymer 2 are from about 5%to about 10%, about 10% to about 15%, or about 15% to about 20%synthetic superabsorbent polymer. In one embodiment, the blend includesbetween approximately 20% and approximately 30% modified biopolymer andbetween approximately 70% and approximately 80% synthetic polymer.Alternatively, the blend includes between approximately 30% andapproximately 60% modified biopolymer and between approximately 40% andapproximately 70% synthetic polymer. In yet another alternative, anyblend percentage of modified biopolymer and synthetic polymer isutilized. Examples of synthetic polymers used in blending include, butare not limited to, sodium polyacrylate, potassium polyacrylate, alkylpolyacrylate, any other acrylate-based superabsorbent polymers,acrylamides, and polyacrylamides. In other embodiments, the modifiedbiopolymer is blended with non-synthetic SAPs, such aspolysaccharide-based SAPs, including cellulose or starch-based SAPs,glutamic acid-based polymers such as polyglutamic acid and otherpolymers created by fermentation. As used in the present application,“blending” refers to physical blending (i.e., physically mixing two ormore polymers) or chemical blending through reaction or compounding.

In a preferred embodiment, the biopolymer is a starch. Exemplarystarches include, but are not limited to, corn starch, potato starch,tapioca starch, and pea starch. Other starches utilized in the presentinvention include wheat starch, cassava starch, rice starch, sorghumstarch, and/or barley starch. In one embodiment, the starch has anamylopectin content of about 70% w/w or more and an amylose content ofabout 30% w/w or less. In another embodiment, the starch has anamylopectin content of at least 70%, at least 75%, at least 80%, nogreater than 80%, or no greater than about 85% w/w and an amylosecontent of less than 30%, less than 25%, less than 20%, no less than20%, or no less than about 15% w/w. In yet another embodiment, thestarch has an amylopectin content of less than 90% w/w.

In a further preferred embodiment, the biopolymer includes industrialgrade corn starch manufactured from Zea mays indentata (commonlyreferred to as “dent” corn or “field” corn). The corn starch of thepresent invention includes an amylose content of approximately 30% w/wand an amylopectin content of approximately 70% w/w, and morespecifically an amylose content of about 27% w/w and an amylopectincontent of about 73% w/w. However, the content of the corn starch isoperable to vary from between about 70% to about 75% amylopectin w/w andbetween about 25% to about 30% amylose w/w. Notably, the corn starchutilized in the present invention does not have an amylopectin contentof 90% w/w or over 90% w/w. Waxy starches, such as waxy corn starch,typically have an amylopectin content of 100% w/w, approximately 100%w/w, or at least 90% w/w, such as the starches described in U.S. Pat.No. 8,710,212. Notably, the waxy starches described in U.S. Pat. No.8,710,212 are much more expensive than the starches utilized in thepresent invention and have higher amylopectin content (w/w) than thestarches utilized in the present invention. The higher amylopectincontent of these waxy starches (at least 90% w/w) accordingly provideshigher molecular weight molecules, which traditionally provide betterperformance (free swell capacity, centrifuge retention capacity, etc.)compared to non-waxy or regular industrial grade corn starches. The FSCof the absorbent material in the '212 patent is at least 13 g/g and theCRC is at least 10 g/g in a saline solution. However, the modifiedbiopolymers of the present invention advantageously provide abiocompostable superabsorbent polymer with at least 75% biobased carboncontent, and more preferably between at least 80% biobased carboncontent or at least 85% biobased carbon content, with a FSC of at least30 g/g, a CRC of at least 15 g/g, and an AUL at 0.7 psi of at least 11g/g. In another embodiment, the biocompostable superabsorbent polymerhas approximately 100% or 100% biobased carbon content.

Due to the cost prohibitive nature of waxy corn starch for use inhygiene products, the present invention preferably does not utilize waxycorn starch or any starch with an amylopectin content of greater than90% for the starch-based modified biopolymer of the present invention.Alternatively, the present invention utilizes a mix of industrial or“dent” corn starch and waxy corn starch, with the amylopectin content ofthe mix of starches being less than 90%.

In another preferred embodiment, the biopolymer includes potato starch,which includes an amylopectin content of approximately 80% w/w and anamylose content of approximately 20% w/w. However, the content of thepotato starch or any other botanical-based starch is operable to varyfrom between about 15% to about 20% amylose w/w and between about 80% toabout 85% amylopectin w/w. In another embodiment, the amylose content oftapioca starch is between about 15% to about 18%, and correspondinglythe amylopectin content of tapioca starch is between about 82% to about85%.

In one embodiment, the starch is dissolvable in water (e.g.,pre-gelatinized starch). In another embodiment, the starch is steamexploded to form a pre-gelatinized starch. In yet another embodiment,the starch has a reduced degree of crystallinity compared to a nativestarch.

In another preferred embodiment, the biopolymer is a chitosan. Thechitosan preferably has a degree of deacetylation of about 50% to about100%. In one embodiment, the chitosan has a degree of deacetylation ofat least 50%, at least 55%, at least 60%, at least 65%, at least 70%, atleast 75%, at least 80%, at least 85%, at least 90%, at least 95%, or atleast 100%. In another embodiment, the chitosan has a degree ofdeacetylation in a range of about 70% to about 100% or at least 80%. Inyet another embodiment, the chitosan has a molecular weight of at least80,000 Daltons.

In one embodiment, the biopolymer is charge-modified according to amethod described herein (e.g., by reacting the biopolymer with at leastone charge-modifying agent in a homogeneous reaction blend). In oneembodiment, the biopolymer naturally carries a charge (i.e., thebiopolymer is natively charged in that the charge is present on thebiopolymer not through a method of the present invention). In anotherembodiment, a method of the present invention changes the charge presenton a biopolymer (e.g., type and/or amount of charge). In still anotherembodiment, a charge-modified biopolymer is soluble (e.g., partially orfully soluble) in a polar solvent (e.g., water and/or a polar organicsolvent at room temperature and/or a nonpolar solvent at roomtemperature. In yet another embodiment, the charge-modified biopolymeris at least 70% soluble in a polar and/or a nonpolar solvent at roomtemperature. In one embodiment, solubility is used as an indicationand/or a characteristic of a degree of charge modification.

“Charge-modifying agent” as used herein refers to a molecule or compoundincluding a first moiety that reacts with an amine and/or hydroxyl groupof the biopolymer and a second moiety that is positively charged ornegatively charged under suitable conditions (e.g., at a certain pH).“Moiety” as used herein, refers to a portion of a molecule or compoundhaving a particular functional or structural feature. For example, amoiety is a functional group or a reactive portion of a compound. Asthose of skill in the art recognize, a strong acidic moiety (e.g.,—SO₃H) or a weak acidic moiety (e.g., —COOH) form a negatively chargedmoiety and a strong basic moiety (e.g., —NH₃OH) or a weak basic moiety(—NH₂) form a positively charged moiety.

In one embodiment, the at least one charge-modifying agent includes atleast one moiety that is a positively charged group, such as, but notlimited to, a primary amine, secondary amine, tertiary amine, quaternaryammonium, sulfonium, and/or phosphonium group. Exemplarycharge-modifying agents that have a positively charged moiety include,but are not limited to, ethylene imine, N-(2-hydroxyethyl) ethyleneimine, cyanamide, beta-morpholinoethyl chloride, beta-diethylaminoethylchloride, S-diethyl amino 1,2-epoxypropane dimethyl aminoethylmethacrylate, epoxy 3-methyl ammonium, glycidyltrimethylammoniumchloride (e.g., QUAB® 151), chlorohydrin (e.g., QUAB® 188),N-(2,3-epoxypropyl) trimethyl ammonium chloride, (4-chlorobutene-2)trimethyl ammonium chloride, 2-chloroethyl methyl ethyl sulfoniumiodide, and/or Z-chloroethyl tributylphosphonium chloride. In anotherembodiment, the charge-modifying agent is a tertiary amino alkyl group,a hydroxyalkyl group, a quaternary ammonium alkyl group, or ahydroxyalkyl group.

In one embodiment, a positively charged moiety is introduced into and/oronto a biopolymer by reacting the biopolymer and the charge-modifyingagent in a homogeneous reaction blend. This reaction optionally occursin the presence of a catalyst. In another embodiment, this reaction is adry melt process and/or is an etherification or esterification reaction.

Additionally, or alternatively, the at least one charge-modifying agentincludes at least one moiety that has a negatively charged group, suchas, but not limited to, a carboxyl, a sulfonate, a sulfate, and/or aphosphate group (e.g., sodium tripolyphosphate, phosphate esters, etc.).Exemplary charge-modifying agents that have a negatively charged moietyinclude, but are not limited to, acids (e.g., glacial acetic acid,ethylenediaminetetraacetic acid (EDTA), citric acid, and/or diethylenetriamine pentaacetic acid (DTPA)); mono-halogen substituted carboxylicacids (e.g., monochloroacetic acid); acetates (e.g., sodiummonochloroacetate); anhydrides (e.g., succinic anhydride, maleicanhydride, citraconic anhydride, and/or octenyl succinicanhydride);alkyl esters of acrylic acid, crotonic acid or itaconic acid (e.g.,methyl and ethyl esters of acrylic acid, crotonic acid, or itaconicacid); acrylonitrile and its derivatives; sodium periodate; sulfones;and/or sulfonic acids (e.g., halo alkane sulfonic acids,chlorooxypropane sulfonic acid, epoxypropane sulfonic acid,chlorooxypropane sulfonic acid, epoxypropane sulfonic acid, ethenesulfonic acid, and/or salts thereof).

FIG. 8 illustrates a FTIR spectrum for unmodified industrial grade cornstarch. FIG. 9 illustrates FTIR spectrum for carboxymethyl starchaccording to one embodiment of the present invention, showing the peakat approximately 1596 cm⁻¹ from the carbonyl bond in the carboxymethylsubstituent attached to the starch backbone. Thus, the present inventionprovides a carboxymethyl corn starch based modified biopolymer accordingto one embodiment of the present invention.

In one embodiment, a negatively charged moiety is introduced into thebiopolymer by reacting the biopolymer and the at least onecharge-modifying agent in a homogeneous reaction blend in the presenceof an alkaline catalyst. In one example, the charge-modifying agent isacrylonitrile and the reaction of the biopolymer and the acrylonitrilein the presence of an alkaline catalyst is followed by hydrolysis of thecyanoethyl groups. In another example, the charge-modifying agent issodium periodate, and the reaction with the biopolymer is followed by atreatment to transform the carbonyl groups into carboxyl groups (e.g.,by treating with sodium chlorite, sodium bisulfite, and/or potassiumbisulfite). In yet another embodiment, both carboxyl and sulfonategroups are introduced into a biopolymer by reacting the biopolymer withan anhydride of an unsaturated acid (e.g., maleic acid) and a bisulfite.The bisulfite is reacted with the unsaturated bond of the polysaccharidehalf ester.

In one embodiment, one or more of the at least one charge-modifyingagent reacts with an amine and/or hydroxyl group of the biopolymer toprovide a charge-modified biopolymer. In one embodiment, thecharge-modified biopolymer is cationic (i.e., has a net positive charge)or is anionic (i.e., has a net negative charge). In another embodiment,the charge-modified biopolymer contains both positively and negativelycharged moieties.

In one embodiment, the biopolymer is crosslinked by reacting at leastone crosslinking agent with the biopolymer and optionally with at leastone different biopolymer that is optionally charge-modified. In anotherembodiment, the at least one crosslinking agent is reacted with at leastone charge-modified biopolymer. “Crosslinking agent” as used hereinrefers to a compound that links two or more biopolymer chains and/orportions of the biopolymer together, the biopolymer optionally beingcharge-modified. In one embodiment, the linkage is achieved via acovalent bond or an ionic bond. In another embodiment, the linkage isthrough a moiety or group of the biopolymer or different biopolymers.

Crosslinking agents include, but are not limited to an acid including anorganic acid or an inorganic acid. Examples of acids includedicarboxylic acid, tricarboxylic acid including oxalic acid, malonicacid, citric acid, succinic acid, glutaric acid, adipic acid, pimelicacid, fumaric acid, maleic acid, malic acid, tartaric acid,2-acrylamido-2-methyl-1-propanesulfonic acid), a sulfonic acidderivative (e.g., sodium 4-vinylbenzenesulfonate, 3-sulfopropylmethacrylate potassium salt,[2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxidesalt, [3-(methacryloylamino)propyl]dimethyl(3-sulfopropyl)ammoniumhydroxide salt, hydrochloric acid and aluminum chloride. Othercrosslinking agents include a sodium phosphate (e.g., sodiumtrimetaphosphate, sodium tripolyphosphate), a borate (e.g., sodiumborate, sodium tetraborate, disodium tetraborate), an ionic crosslinker(e.g., calcium chloride, calcium hydroxide, etc.), a glycidyl ether(e.g., allyl glycidyl ether), an ammonium salt (e.g.,glycidyltrimethylammonium chloride,(3-chloro-2-hydroxypropyl)trimethylammonium chloride,[2-(Acryloyloxy)ethyl]trimethylammonium chloride,(3-acrylamidopropyl)trimethylammonium chloride,[3-(methacryloylamino)propyl]trimethylammonium chloride,[2-(methacryloyloxy)ethyl]trimethylammonium chloride,diallyldimethylammonium chloride), a (meth)acrylic acid (e.g., acrylicacid, methacrylic acid), a (meth)acrylate (e.g., glycidyl methacrylate,glycidyl acrylate), a (meth)acrylate derivate (e.g.,N-(3-aminopropyl)methacrylamide hydrochloride, 2-aminoethyl methacrylatehydrochloride), an ester (e.g., ethylene carbonate), a polyol (e.g.,propane diol), an oxazolidinone (e.g., 2-hydroxyethyl-2-oxazolidinone),a metal crosslinker including a salt of a metal cation plus an anion,with the anion being organic or inorganic with examples of metalcrosslinkers including metal lactates (e.g., aluminum lactate), zincchloride, magnesium acetate, and magnesium acetate tetrahydrate and/oran anhydride (e.g., succinic anhydride, maleic anhydride). In oneembodiment, the crosslinker is a mix of two or more of the above recitedcrosslinkers, including by way of example and not limitation, a mix ofcitric acid and adipic acid. In yet another embodiment, the crosslinkingagent is non-toxic. Crosslinkers include polycarboxylic acids (including0.8% w/w citric acid, and 1.2% w/w citric acid, succinic acid including0.8% w/w succinic acid and 1.2% w/w succinic acid, and adipic acidincluding 0.8% w/w adipic acid and 1.2% w/w adipic acid).

In one embodiment, the at least one charge-modifying agent dehydrates toyield an anhydride when heated inside an extruder. The free hydroxylgroups from a biopolymer (e.g., starch) present in the reaction mixturereact with the anhydride to form starch citrate. In another embodiment,additional dehydration of the biopolymer and/or the charge-modifiedbiopolymer allows for crosslinking of the biopolymer and/or thecharge-modified biopolymer to occur. In yet another embodiment,crosslinking of the biopolymer and/or the charge-modified biopolymer isachieved due to the heat inside the extruder and/or during a posttreatment process (e.g., a thermal post-treatment process). In stillanother embodiment, the charge-modified biopolymer is prepared using aring-opening polymerization of anhydrous acids.

In one embodiment, the modified biopolymer includes a plurality of poresor void spaces formed therein. In another embodiment, the pores or voidspaces have an average diameter of about 0.1 micron to about 500 microns(e.g., about 10 microns to about 500 microns, about 50 microns to about500 microns, about 100 microns to about 400 microns, or about 250microns to about 500 microns). In yet another embodiment, the pores orvoid spaces have an average diameter of about 0.1 micron, about 1micron, about 10 microns, about 25 microns, about 50 microns, about 100microns, about 150 microns, about 200 microns, about 250 microns, about300 microns, about 350 microns, about 400 microns, about 450 microns, orabout 500 microns.

In one embodiment, the modified biopolymer has a net positive charge(i.e., is cationic) or a net negative charge (i.e., is anionic). Inanother embodiment, the modified biopolymer is a polyampholyte. In yetanother embodiment, the modified biopolymer is a polyelectrolyte that ishydrophilic (e.g., due to the number of ionizable groups present on themodified biopolymer). In a preferred embodiment, the modified biopolymeris a superabsorbent. In one embodiment, the superabsorbent absorbs afluid in an amount of at least 15 times (e.g., 20×, 30×, 40×, 50×, 100×,etc.) relative to its weight. In another embodiment, the superabsorbentabsorbs a saline solution in an amount of at least 20 times (e.g., 25×,30×, etc.) relative to its weight at room temperature and/or water in anamount of at least 35 times or more (e.g., 40×, 45×, etc.) relative toits weight at room temperature. In yet another embodiment, the cornstarch biopolymer superabsorbent of the present invention has a swellingcapacity with a minimum of 13 g/g, and an exemplary swelling capacity ofat least 23 g/g in defibrinated sheep's blood according to a modifiedFSC ran with defibrinated sheep's blood, compared to traditionalsynthetic swelling capacity with a minimum of 5 g/g and a maximum of 22g/g.

The modified biopolymer is preferably a biosorbent. A “biosorbent” asused herein refers to an absorbent (e.g., that is utilized in theremoval of a fluid) and/or an adsorbent (e.g., that is utilized as anion exchange material and/or metal chelating material). In a preferredembodiment, the biosorbent is a superabsorbent.

The modified biopolymer preferably has an absorbency under load (AUL) at0.7 psi of at least 5 g/g. The AUL is tested according to INDA/EDANAStandard WSP 242.2.R3 entitled “Gravimetric Determination ofPermeability Dependent Absorption Under Pressure”, which is incorporatedherein by reference in its entirety.

The modified biopolymer preferably has a charge density of about 3 meq/gor more (e.g., as determined by titration). In one embodiment, chargedensity is determined by titration as described in Example 1.1. In oneembodiment, the modified biopolymer has a charge density of at least 3meq/g, at least 3.5 meq/g, at least 4 meq/g, at least 4.5 meq/g, atleast 5 meq/g, at least 5.5 meq/g, at least 6 meq/g, at least 6.5 meq/g,at least 7 meq/g, at least 7.5 meq/g, at least 8 meq/g, at least 8.5meq/g, at least 9 meq/g, at least 9.5 meq/g, or at least 10 meq/g asdetermined by titration. In a preferred embodiment, the modifiedbiopolymer has a charge density of at least about 5 meq/g as determinedby titration.

In one embodiment, the modified biopolymer has the charge modificationsubstantially uniformly distributed throughout the bulk of the modifiedbiopolymer. Thus, the modified biopolymer has a substantially uniformcharge density. In another embodiment, the uniformity of the chargedensity of a modified biopolymer is determined by evaluating thepresence of insoluble materials after exposure of the modifiedbiopolymer to a solvent (e.g., water). In yet another embodiment,observation of particles (such as, for example, 1-10 μm particles)indicates the lack of charge modification within the particles and/ormodified biopolymer. In still another embodiment, charge densitydistribution on the modified biopolymer is determined and/or evaluatedusing one or more spectrographic analytical techniques such as, but notlimited to, EDS, Electron Phenomenological Spectroscopy (EPS), and/orTime-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) of the chargedmoiety's counter ion. In one embodiment, an uneven distribution ofcounter ions and/or the presence of particles (e.g., 1-10 μm particles)lacking the counter ion indicates non-uniformity and/or inhomogeneity inregard to the distribution of the charge on the modified biopolymer.

The modified biopolymer of the present invention preferably has anincreased charge density and/or degree of crosslinking compared to amodified biopolymer (e.g., a crosslinked, charge-modified biopolymer)prepared using a conventional method. “Conventional method” as usedherein in reference to a method for preparing a modified biopolymerrefers to a method for preparing a modified biopolymer in which thebiopolymer is a solid (e.g., a particulate) and a reaction of thebiopolymer with at least one reactant in the method occurs at a solidinterface of the biopolymer. In one embodiment, a conventional method isa method that does not involve a melt extrusion process, such as areactive extrusion process. In another embodiment, a conventional methodis a semi-dry process, a multi-phase process, a process having a liquidinterface with a solid material, and/or a heterogeneous process. Instill another embodiment, a conventional method is a heterogeneous wetchemistry method and/or a multi-phase process. Conventional methodsutilized in the present invention typically form homogenous reactionblends once all reactants are added.

The modified biopolymer preferably has a charge density and/or degree ofcrosslinking that is increased by at least 5% or more compared to amodified biopolymer prepared using a conventional method. In oneembodiment, the modified biopolymer has a charge density and/or degreeof crosslinking that is increased by at least 5%, at least 10%, at least15%, at least 20%, at least 25%, at least 30%, at least 35%, at least40%, at least 45%, at least 50%, at least 55%, at least 60%, at least65%, at least 70%, at least 75%, at least 80%, at least 85%, at least90%, at least 95%, at least 100%, at least 150%, or at least 200% to amodified biopolymer prepared using a conventional method.

In one embodiment, a degree or an amount of crosslinking present in themodified biopolymer provides mechanical rigidity to the modifiedbiopolymer and/or correlates with a degree of mechanical rigidity in themodified biopolymer.

The modified biopolymer preferably has a degree of substitution of atleast 0.01 (e.g., in a range of about 0.01 to about 0.3). In a preferredembodiment, the modified biopolymer has a degree of substitution ofbetween about 0.3 to about 0.6, and more preferably between about 0.4 toabout 0.6. In another embodiment, the degree of substitution is lessthan about 0.5. In other alternatives, the degree of substitution isabout 0.6, about 0.5, and about 0.42. In yet another embodiment, thedegree of substitution is measured by nitrogen content (e.g., foranionic modified biopolymers).

The modified biopolymer preferably is biocompostable and/orbiodegradable. In one embodiment, the modified biopolymer degrades by atleast 90% relative to a cellulose control in less than 180 daysaccording to a modified ASTM D5338, where smaller sample sizes were runon smaller, more precise equipment compared to traditional ASTM D5338.Specifically, at least the modified biopolymers described in Example 11below are biocompostable according to ASTM D5338. ASTM D5338 is astandard biodegradation test that measures the aerobic biodegradation ofplastic materials under controlled composting conditions; ASTM D5338 isa test method for meeting the biocompostability standard of the ASTMD6400 standard. In a preferred embodiment, the modified biopolymerdegrades by at least 90% in less than 90 days relative to cellulose. Themodified biopolymers of the present invention are biodegradable and/orbiocompostable regardless of the starch utilized, wherein starchesinclude but are not limited to, corn starch, potato starch, tapiocastarch, and pea starch. FIG. 10 is a chart illustrating the percentdegradation of two modified corn starch based biopolymers having atleast 80% biobased carbon content, an amylose content of approximately30% w/w, and an amylopectin content of approximately 70% w/w compared toanalytical grade cellulose with particles having diameters no greaterthan 20 microns and pellets of polyethylene. Notably, the BiorenewableCarbon Index (BCI) for the modified biopolymers estimated 84% to 85%biobased carbon content, and the ASTM D6866 Carbon 14 Test measured85.9% biobased carbon content for these modified biopolymers. The ASTMD5338 testing was conducted at the University of Georgia's Center forBiodegradable Polymers and Additives, and the ASTM D6866 Carbon 14 Testwas conducted at Beta Analytic in Florida. As illustrated in FIG. 10both modified biopolymers of the present invention showed over 90%degradation in less than 90 days relative to a cellulose control(analytical grade cellulose), and are accordingly biocompostableaccording to ASTM D5338 guidelines. Notably, both modified biopolymersof the present invention degraded over 80% in 70 days, over 60% in 50days, over 40% in 45 days, and over 20% in 30 days relative to acellulose control. Both modified biopolymers of the present inventionalso degrade over 70% in 70 days, over 50% in in 50 days, over 35% in 45days, and over 15% in 30 days relative to a cellulose control. In otherwords, both modified biopolymers exhibited over 40% degradation in 60days and over 60% degradation in 90 days relative to a cellulosecontrol. Both modified biopolymers degraded more than the cellulosecontrol after approximately 70 days. The aforementioned degradation dataapplies to modified biopolymers with a particle size range of 150microns to 350 microns. In another embodiment, another modifiedbiopolymer of the present invention with a particle size range of 150microns to 850 microns degrades over 40% in 35 days, over 45% in 85days, and over 50% in 90 days. In another embodiment, ASTM D6400 (ASTMD6400-19, Standard Specification for Labeling of Plastics Designed to beAerobically Composted in Municipal or Industrial Facilities, ASTMInternational, West Conshohocken, Pa., 2019), ISO 14855 (ISO14855-2:2018, Determination of the Ultimate Aerobic Biodegradability ofPlastic Materials Under Controlled Composting Conditions—Method byAnalysis of Evolved Carbon Dioxide—Part 2: Gravimetric Measurement ofCarbon Dioxide Evolved in a Laboratory-Scale Test, InternationalOrganization for Standardization, Geneva, Switzerland, 2018), and/orASTM D5338 (ASTM D5338-15, Standard Test Method for Determining AerobicBiodegradation of Plastic Materials Under Controlled CompostingConditions, Incorporating Thermophilic Temperatures, ASTM International,West Conshohocken, Pa., 2015), each of which is incorporated herein byreference in its entirety, are used to determine biocompostabilityand/or biodegradability. The modified corn starch based biopolymers arebiocompostable according to ASTM D5338 guidelines. According to theBiorenewable Carbon Index (BCI), these modified biopolymers includebetween approximately 84% to approximately 85% biobased carbon content.The BCI method provides a quantitative estimate of the number ofbioderived carbons in the final product as a percentage of total carbonsin the final product. As an example, sodium polyacrylate (a syntheticSAP) has 0 bio-derived carbons out of three total carbons in each sodiumacrylate monomer. In contrast, glucose has 6 bio-derived carbons out ofthe total 6 carbons in each glucose monomer. According to the ASTMD6866-18 Carbon 14 Test, the modified corn starch based biopolymersinclude about 85.9% biobased carbon content, which meets the criteriafor the four-star rating of the TUV Austria OK biobased certification(formerly known as the Vincotte Bioderived certification), with thefour-star rating requiring that composition include greater than 80%biobased carbon content. The ASTM D6866 Carbon 14 Test was completed bythe Beta Analytic Biobased and Biogenic Carbon Testing LaboratoryISO/IEC 17025:2005 (Testing accreditation PJLA #59423, Miami, Fla.).

In one embodiment, the modified biopolymer includes a plurality of poresand/or void spaces. The modified biopolymer of the present invention hasan increased porosity and/or pore size compared to a modified biopolymerprepared using a conventional method. In one embodiment, the porosity isincreased by increasing the number of pores or void spaces. The pores orvoid spaces are substantially the same size (e.g., varying in size ordiameter by less than about 20%) in one embodiment. Alternatively, thepores or void spaces are different sizes. In one embodiment, themodified biopolymer has a porosity and/or pore size that is increased byat least about 5% or more compared to a modified biopolymer preparedusing a conventional method. In some embodiments, the modifiedbiopolymer has a porosity and/or pore size that is increased by at least5%, at least 10%, at least 15%, at least 20%, at least 25%, at least30%, at least 35%, at least 40%, at least 45%, at least 50%, at least55%, at least 60%, at least 65%, at least 70%, at least 75%, at least80%, at least 85%, at least 90%, at least 95%, at least 100%, at least150%, or at least 200% compared to a modified biopolymer prepared usinga conventional method.

In one embodiment, the modified biopolymer has a more uniform porosityand/or pore size compared to a modified biopolymer prepared using aconventional method. A more uniform porosity includes a more uniformlyor evenly dispersed number of pores or void spaces throughout themodified biopolymer. In another embodiment, a more uniform pore sizeincludes a more uniform diameter of the pores or void spaces throughoutthe modified biopolymer. In yet another embodiment, the porosity and/orpore size of the modified biopolymer of the present invention is moreuniform compared to the porosity and/or pore size of a modifiedbiopolymer prepared using a conventional method, and varies by less thanabout 20% (e.g., by less than 20%, less than 15%, less than 10%, lessthan 5%) as determined by comparing two or more defined areas of themodified biopolymer compared to two or more defined areas of themodified biopolymer prepared using a conventional method.

In one embodiment, the modified biopolymer sequesters, binds, absorbs,chelates, uptakes, adsorbs, and/or the like a fluid (e.g., water,hydrocarbons, oils, alcohols, aqueous solutions, non-aqueous solutions,ionic solutions such as salt solutions, biological fluids such as bloodand/or urine, gases, waste water, and/or fracking fluids), a chargedspecies (e.g., ions such as potassium ions (K⁺), calcium ions (Ca²⁺),sodium ions (Na⁺), chloride ions (Cl⁻), fluoride ions (F⁻), phosphiteions (PO₃ ³⁻), sulfate ions (SO₄ ²⁻), sulfite ions (SO₃ ²⁻), phosphateions (PO₄ ³⁻), polyatomic ions, and/or metal ions; charged peptides,polypeptides, nucleic acids, and/or oligonucleotides; and the like),and/or a metal (e.g., lead, mercury, cadmium, arsenic, copper, chromium,thallium, selenium, zinc, calcium, magnesium, silver, boron, and thelike). In another embodiment, the modified biopolymer physically adsorbsa species present in the fluid (e.g., an ionic species and/or a metal).In yet another embodiment, the species is dissolved in the fluid. Instill another embodiment, the modified biopolymer binds a fluid, chargedspecies, and/or metal (e.g., via hydrogen bonding, covalent bonding, vander Waals/adsorptive binding, and/or ionic bonding).

In one embodiment, the modified biopolymer sequesters, binds, absorbs,chelates, uptakes, adsorbs, and/or the like an ion and/or a metal. Inanother embodiment, the metal is in an ionized form (e.g., in the formof a salt). As those skilled in the art recognize, a metal may exist ina number of ionized forms (e.g., monovalent, divalent, polyvalent,anionic, and/or cationic forms). Further exemplary ions and/or metals,in any ionized form, that the modified biopolymer sequesters, binds,absorbs, chelates, uptakes, adsorbs, and/or the like include, but arenot limited to, sodium, potassium, lithium, ammonium, barium, strontium,manganese, silver, cesium, zinc, cadmium, selenium, calcium, magnesium,iron, radium, mercury, copper, lead, nickel, chromium, arsenic, gold,uranium, chloride, bromide, nitrate, iodide, carbonate, sulphate, and/orphosphate.

In one embodiment, the modified biopolymer sequesters, binds, absorbs,chelates, uptakes, adsorbs, and/or the like an organic compound.Exemplary organic compounds include, but are not limited to, toluene,xylenes, benzene, ethylbenzene, trimethylbenzene, acetone, and/ormethanol.

The modified biopolymer of the present invention sequesters, binds,absorbs, chelates, uptakes, adsorbs, and/or the like an increased amountor concentration of a fluid, a charged species, and/or a metal comparedto a modified biopolymer prepared using a conventional method. In apreferred embodiment, the modified biopolymer of the present inventionsequesters, binds, absorbs, chelates, uptakes, adsorbs, and/or the likean increased amount or concentration of a fluid, charged species, and/ora metal by at least about 5% or more compared to a modified biopolymerprepared using a conventional method. In some embodiments, the modifiedbiopolymer sequesters, binds, absorbs, chelates, uptakes, adsorbs,and/or the like an increased amount or concentration of a fluid, chargedspecies, and/or a metal by at least 5%, at least 10%, at least 15%, atleast 20%, at least 25%, at least 30%, at least 35%, at least 40%, atleast 45%, at least 50%, at least 55%, at least 60%, at least 65%, atleast 70%, at least 75%, at least 80%, at least 85%, at least 90%, atleast 95%, at least 100%, at least 150%, or at least 200% compared to amodified biopolymer prepared using a conventional method.

As previously detailed, the modified biopolymer is preferably formed ofa starch and/or a chitosan. In one embodiment, the starch and/or thechitosan is charged-modified and the starch and the chitosan arecrosslinked with each other to form a crosslinked, charged-modifiedstarch-chitosan biopolymer.

The modified biopolymer is preferably formed in a homogeneous reactionblend. A homogeneous reaction blend is a melted blend of all componentsor reactants in a single phase. In one embodiment, the homogeneousreaction blend is obtained using an extruder. In another embodiment, thehomogeneous reaction blend is obtained using a reactive extrusionprocess in an extruder.

In one embodiment, the homogeneous reaction blend is in the form of asingle liquid phase. In another embodiment, the homogeneous reactionblend provides a uniform distribution of the components or reactants ascompared to a conventional method. In yet another embodiment, formationof the homogeneous reaction blend provides a chemical reaction thatoccurs more uniformly and/or completely as compared to a conventionalmethod. In one embodiment, the biopolymer in the homogeneous reactionblend is a melted thermoplastic. In a preferred embodiment, thehomogeneous reaction blend does not include ethanol. The homogeneousreaction blend preferably does not include ethanol in the extrusionmixture so that the extrusion mixture is purposefully substantially orcompletely gelatinized or gelatinous and is not in granular form. Inanother embodiment, the biopolymer reacts thermo-mechanically and/orchemically with one or more reagents to form a charge-modifiedbiopolymer. In yet another embodiment, the charge-modified biopolymer isthermoplastic and/or a viscoelastic material. In still anotherembodiment, hydrogen bonding and/or crystalline domains initiallypresent in the biopolymer are removed. Advantageously, this allows forall or substantially all portions of the biopolymer to be available forchemical reaction (e.g., via charge-modification and/or crosslinking).

A “reactive extrusion process” as used herein refers to a process inwhich a biopolymer is both chemically and physically modified. In oneembodiment, the reactive extrusion process provides for a chemicalmodification of the biopolymer, such as, but not limited to, graftingonto the biopolymer, crosslinking of the biopolymer, functionalizationof the biopolymer, and/or charge-modification of the biopolymer. Inanother embodiment, the reactive extrusion process provides forpolymerization and/or branching of the biopolymer. In yet anotherembodiment, the polymerization and/or branching is with a differentbiopolymer to provide a copolymer. An exemplary physical modification ischanging the form of the biopolymer, such as, but not limited to, from apowder, particulate, and/or solid form to a molten or melted form.

In one embodiment, a biopolymer and at least one charge-modifying agentare reacted in a homogeneous reaction blend to form a charge-modifiedbiopolymer. In another embodiment, the biopolymer and the at least onecharge-modifying agent are combined, optionally with a plasticizerand/or catalyst, to form the homogeneous reaction blend. In yet anotherembodiment, at least two different biopolymers are reacted with at leastone charge-modifying agent in a homogeneous reaction blend. Optionally,one or more of the at least two different biopolymers is charge-modifiedprior to the reacting step.

In one embodiment, the at least one charge-modifying agent is present ina homogeneous reaction blend in an amount of about 5% to about 200% ormore by weight of at least one biopolymer present in the homogeneousreaction blend. In one embodiment, the at least one charge-modifyingagent is present in a homogeneous reaction blend in an amount of atleast about 75% by weight of at least one biopolymer present in thehomogeneous reaction blend. In another embodiment, the at least onecharge-modifying agent is present in a homogeneous reaction blend in anamount of at least about 75% by weight of a biopolymer and provides amodified biopolymer having a charge density of at least 1.5 meq/g (e.g.,as determined by titration).

In one embodiment, a biopolymer and at least one crosslinking agent arereacted in a homogeneous reaction blend to form a crosslinkedbiopolymer. In another embodiment, the biopolymer and the at least onecrosslinking agent are combined, optionally with a plasticizer and/orcatalyst, to form the homogeneous reaction blend. In yet anotherembodiment, at least two different biopolymers are reacted with at leastone crosslinking agent in the homogeneous reaction blend.

Alternatively, a biopolymer (e.g., starch), a polymer (e.g.,polyacrylate), and at least one crosslinking agent are reacted in ahomogenous reaction blend to form a graft copolymer (e.g.,starch-acrylate copolymer). In one embodiment, the biopolymer is acharge-modified biopolymer. In another embodiment, cyclic esterco-polymers such as poly(caprolactone) are utilized to form graftcopolymers. Cyclic ester co-polymers are described in U.S. Pat. No.5,540,929, which is incorporated herein by reference in its entirety.Other co-polymers operable to be utilized in the present inventioninclude polystyrenes, polybutadienes, or any other molecule including aterminal alkene operable to be grafted through a free radical mechanism.

In one embodiment, the homogeneous reaction blend is formed using atleast two different biopolymers. In another embodiment, the homogeneousreaction blend is formed using a charge-modified biopolymer and at leastone different biopolymer. In yet another embodiment, one or more of theat least one different biopolymer is charge-modified. When twobiopolymers are present in the homogeneous reaction blend, a firstbiopolymer is present in the homogeneous reaction blend in an amount ofabout 10% to about 200% or more by weight of a second biopolymer presentin the homogeneous reaction blend. In still another embodiment, thefirst biopolymer is present in the homogeneous reaction blend in anamount of about 10%, about 20%, about 30%, about 40%, about 50%, about60%, about 70%, about 80%, about 90%, about 100%, about 110%, about120%, about 130%, about 140%, about 150%, about 160%, about 170%, about180%, about 190%, about 200%, or more by weight of the second biopolymerpresent in the homogeneous reaction blend.

In one embodiment, the first biopolymer and the second biopolymer arepresent in the homogeneous reaction blend in a ratio in a range of 0.1:1to 4:1 (first biopolymer: second biopolymer) (e.g., in a ratio in arange of 0:5:1 to 2:1 or 1:1 to 3:1). In another embodiment, the firstbiopolymer and the second biopolymer are present in the homogeneousreaction blend in a ratio of about 0.5:1, 1:1, or 1:0.5.

In one embodiment, a biopolymer and at least one charge-modifying agentare reacted in a homogeneous reaction blend to form a charge-modifiedbiopolymer. The charge-modified biopolymer is then reacted with at leastone crosslinking agent in the homogeneous reaction blend to form acrosslinked, charge-modified biopolymer. In another embodiment, at leasttwo different biopolymers are reacted with at least one charge-modifyingagent in the homogeneous reaction blend to form at least onecharge-modified biopolymer. In yet another embodiment, thecharge-modified biopolymer is crosslinked to one or more of the at leasttwo different biopolymers in the homogeneous reaction blend. The one ormore different biopolymers is optionally charge-modified prior to acombining, a reacting, and/or a crosslinking step. In still anotherembodiment, the biopolymer and the at least one charge-modifying agentare combined to form the homogeneous reaction blend.

In one embodiment, a crosslinked, charge-modified biopolymer is formedusing a first biopolymer and a second biopolymer. In one embodiment, thefirst biopolymer and/or the second biopolymer is charge-modified priorto addition to a homogeneous reaction blend. In another embodiment, thefirst biopolymer and/or the second biopolymer is charge-modified in thehomogeneous reaction blend. In yet another embodiment, chargemodification of the first biopolymer and/or the second biopolymer andsubsequent crosslinking occur in more than one homogeneous reactionblend. In one example, charge modification of the first biopolymeroccurs in a first reaction blend to form a charge-modified firstbiopolymer, charge modification of the second biopolymer occurs in asecond reaction blend to form a charge-modified second biopolymer, andcrosslinking of the charge-modified first biopolymer and thecharge-modified second biopolymer occurs in a third homogeneous reactionblend to form a crosslinked, charge-modified biopolymer.

In one embodiment, one or more steps (e.g., a combining, reaction,and/or crosslinking step) occur simultaneously and/or sequentially withanother step. For example, in one embodiment, a reacting step to form acharge-modified biopolymer occurs simultaneously with a crosslinkingstep to form a crosslinked, charge-modified biopolymer. In anotherembodiment, a crosslinking step to form a crosslinked, charge-modifiedbiopolymer occurs after a reacting step to form a charge-modifiedbiopolymer. In yet another embodiment, a reacting step and acrosslinking step occur in different reaction zones of an extruder.

In one embodiment, the modified biopolymer is produced using acontinuous process. In another embodiment, the reacting and/orcrosslinking steps occur and/or are carried out in a continuous process.A continuous process is one that does not involve intermediate stepsthat stop a reaction in process. Exemplary intermediate steps include,but are not limited to, changing a buffer or providing a wash stepbefore obtaining the product. In yet another embodiment, the continuousprocess is carried out or performed in an extruder optionally using areactive extrusion process. For example, a continuous process includes aprocess in which all reactants are added to an extruder either at thesame time or different times and the process occurs continuously (i.e.,without stopping for intermediate steps) until the modified biopolymeris extruded. In still another embodiment, a continuous process alsoincludes a step that is carried out or performed in an extruder, such asa reacting and/or a crosslinking step.

In one embodiment, the modified biopolymer is produced using acontinuous process followed by a non-continuous process (e.g.,post-treatment). In another embodiment, the modified biopolymer isproduced using a continuous process, a non-continuous process (e.g., abatch process), and optionally a subsequent continuous process. In oneexample, a continuous process is used to prepare a charge-modifiedbiopolymer (e.g., a charge-modified starch), and then thecharge-modified biopolymer undergoes a post-treatment (e.g., optionallya batch process). In another example, the charge-modified biopolymer(e.g., a charge-modified starch) is then reacted with a secondbiopolymer (e.g., chitosan). In one embodiment, the second biopolymer ischarge-modified.

In one example, a charge-modified first biopolymer and a charge-modifiedsecond biopolymer that is different than the charge-modified firstbiopolymer are combined, optionally with at least one plasticizer, atleast one crosslinking agent, and/or at least one catalyst, to form ahomogeneous reaction blend. The charge-modified first biopolymer and thecharge-modified second biopolymer are crosslinked in the homogeneousreaction blend to form a crosslinked, charge-modified biopolymer.

In another example, a first biopolymer, a second biopolymer that isdifferent than the first biopolymer, at least one charge-modifyingagent, at least one plasticizer, and optionally at least one catalystare combined to form a homogeneous reaction blend. The first biopolymerand the second biopolymer are reacted with the at least onecharge-modifying agent to form a charge-modified first biopolymer and acharge-modified second biopolymer. The charge-modified first biopolymerand the charge-modified second biopolymer are crosslinked to form acrosslinked, charge-modified biopolymer.

In yet another example, a first biopolymer, a first charge-modifyingagent, and optionally at least one catalyst are combined to form ahomogeneous reaction blend including a charge-modified first biopolymer.A charge-modified second biopolymer and at least one plasticizer areadded to the homogeneous reaction blend including the charge-modifiedfirst biopolymer. The charge-modified first biopolymer and thecharge-modified second biopolymer are crosslinked to form a crosslinked,charge-modified biopolymer.

In still another example, a first biopolymer, a first charge-modifyingagent, and optionally at least one catalyst are combined to form acharge-modified first biopolymer. A homogeneous reaction blend is formedincluding the charged-modified first biopolymer, a charged-modifiedsecond biopolymer, and at least one plasticizer. The charge-modifiedfirst biopolymer and the charged-modified second biopolymer arecrosslinked to form a crosslinked, charge-modified biopolymer.

In yet another example, a homogeneous reaction blend is formed bycombining a first biopolymer, a second biopolymer that is optionallycharged-modified, and at least one charge-modifying agent. The firstbiopolymer and the at least one charge-modifying agent are reacted inthe homogeneous reaction blend to form a charge-modified biopolymer. Thecharge-modified biopolymer and the second biopolymer are crosslinked inthe homogeneous reaction blend to form a crosslinked, charge-modifiedbiopolymer.

In still another example, a first homogeneous reaction blend is formedby combining a first biopolymer and at least one charge-modifying agent.The first biopolymer and the at least one charge-modifying agent arereacted in the first homogeneous reaction blend to form acharge-modified biopolymer. The charge-modified first biopolymer iscombined with a second biopolymer that is optionally charge-modified toform a second homogeneous reaction blend. The charge-modified firstbiopolymer and the second biopolymer are crosslinked in the secondhomogeneous reaction blend to form a crosslinked, charge-modifiedbiopolymer.

In one embodiment, a reaction (e.g., charge-modification, crosslinking)occurs with faster kinetics than kinetics of the same reaction in aconventional method. In one embodiment, at least one reaction occurs ata speed increased compared to a speed of the same reaction in aconventional method. The modified biopolymer is preferably produced atan overall greater speed of reaction compared to a conventional method.

In one embodiment, at least one plasticizer is present in thehomogeneous reaction blend with the biopolymer and the at least onecharge-modifying agent. In another embodiment, the at least oneplasticizer is combined with the biopolymer and the at least onecharge-modifying agent to form a homogeneous reaction blend. In yetanother embodiment, the at least one plasticizer is present in thehomogeneous reaction blend in an amount of about 10% to about 400% ormore by weight of at least one biopolymer present in the homogeneousreaction blend. In a preferred embodiment, the at least one plasticizeris present in the homogeneous reaction blend in an amount of at leastabout 30% or more by weight of at least one biopolymer (e.g., starch)present in the homogeneous reaction blend. In another preferredembodiment, the at least one plasticizer is present in the homogeneousreaction blend in an amount of at least about 100% or more by weight ofat least one biopolymer (e.g., chitosan, hemicellulose, pectin, and/orsoy protein) present in the homogeneous reaction blend.

In one embodiment, the at least one plasticizer is a low molecularweight non-volatile compound. Additional exemplary plasticizers include,but are not limited to, triphenyl phosphate, camphor oil, amyl acetate,allylurea, citric acid, citrate esters, phthalic acid esters, dioctylphthalate, fatty acid esters, benzoates, tartrates, chlorinatedhydrocarbons, esters of adipic acid, polyols (e.g., glycerol, ethyleneglycol (EG), diethylene glycol (DEG), triethylene glycol (TEG),tetraethylene glycol, polyethylene glycol, propylene glycol (PG),sorbitol, mannitol, xylitol, fatty acids, and/or vegetable oils),lecithin, waxes, amino acids, surfactants, and/or water.

In one embodiment, the at least one plasticizer reduces the glasstransition temperature (T_(g)). In another embodiment, the at least oneplasticizer improves the flexibility, workability, distensibility,and/or processability of a biopolymer (e.g., by lowering the glasstransition temperature (T_(g))). In yet another embodiment, thebiopolymer is not thermoplastic and the glass transition temperature(T_(g)) must be lowered by addition of the at least one plasticizerprior to extrusion.

The at least one plasticizer reduces the tension of deformation,hardness, density, viscosity, and/or electrostatic charge of thebiopolymer and at the same time increases the biopolymer chainflexibility, resistance to fracture, and/or dielectric constant. Otherproperties of the biopolymer that may also be affected by the inclusionof the at least one plasticizer include, but not limited to, degree ofcrystallinity, optical clarity, electric conductivity, fire behaviorand/or resistance to biological degradation. In one embodiment, the atleast one plasticizer allows for the biopolymer to melt and/or becomethermoplastic to provide a single phase. In another embodiment, the atleast one plasticizer disrupts hydrogen bonds present in a crystallinestructure of the biopolymer. In yet another embodiment, disrupting thehydrogen bonds leads to breaking of crystalline domains that preventthermal processing. Advantageously, this allows for the meltprocessability of biopolymers that are not traditionally meltprocessable.

In one embodiment, the homogeneous reaction blend contains at least oneplasticized biopolymer. The at least one plasticized biopolymer allowsfor greater access to moieties throughout the biopolymer. In contrast,in a heterogeneous phase reaction (e.g., in which modified biopolymersare synthesized by a coating process, in a diluted suspension, or with aconcentrated gel solution) there is a limited amount of moieties (e.g.,free hydroxyls) exposed to the reagent as the surface moieties areexposed to the reagent, and the interior moieties are not exposed. Thereaction is thus carried out on the surface of the solid granule asshown in FIG. 1A (e.g., by direct conversion of either thesemi-crystalline granules in aqueous suspension or as a dry process).FIG. 1B shows an exemplary schematic of a homogeneous phase reaction inwhich a biopolymer (e.g., starch) is plasticized using at least oneplasticizer to obtain thermoplastic behavior. Under the action ofthermo-mechanical energy, the starch granule melts. In one embodiment,the at least one plasticizer is adsorbed to the starch by heating themixture. Destruction of the granular structure of the biopolymer occurswith the introduction of mechanical and heat energy. In the presence ofat least one plasticizer, biopolymer granules are transferred to acontinuous phase and moieties (e.g., hydroxyl free groups) are availableto react with the reagent. In another embodiment, the homogeneousreaction blend aids in distributing a modification (e.g., acharge-modification) along a biopolymer chain and/or more uniformlythroughout a biopolymer in contrast to a conventional method, such as,for example, one in which the modification is only achieved at thesurface (e.g., at the surface of a solid biopolymer granule).

A catalyst is optionally present in the homogeneous reaction blend. Inone embodiment, the catalyst and/or the plasticizer is combined with thebiopolymer and the at least one charge-modifying agent to form thehomogeneous reaction blend. In another embodiment, the catalyst ispresent in the homogeneous reaction blend in an amount of about 1% toabout 100% or more by weight of at least one biopolymer present in thehomogeneous reaction blend.

The catalyst accelerates the charge-modification and/or crosslinkingreaction. In one embodiment, the catalyst adjusts the pH to enhanceopening of chemical bonds. Exemplary catalysts include, but are notlimited to, sodium hypophosphite, sodium bisulfate, sodium bisulfite,and/or caustics (e.g., sodium hydroxide, calcium hydroxide, etc.). Inanother embodiment, the charge-modification and/or crosslinking reactionis carried out at a pH in a range of about 9 to about 12, about 10 toabout 12, about 2 to about 7, or about 2 to about 5.

In one embodiment, the catalyst is an initiator. In another embodiment,the catalyst is a photoinitiator. In yet another embodiment, thebiopolymer (e.g., a charge-modified biopolymer) is reacted with at leastone crosslinking agent in the presence of an initiator. Exemplaryinitiators include, but are not limited to, peroxides such as acylperoxides (e.g., benzoyl peroxide), dialkyl or aralkyl peroxides (e.g.,di-t-butyl peroxide, dicumyl peroxide, cumyl butyl peroxide,1,1-di-t-butylperoxy-3,5,5-trimethylcyclohexane,2,5-dimethyl-2,5-di-t-butylperoxy hexane, andbis(t-butylperoxyisopropyl)benzene), ketone peroxides (e.g.,cyclohexanone peroxide and methylethylketone peroxide), ketones (e.g.,1-hydroxy-cyclohexyl-phenyl-ketone,), sodium methoxide, potassiumpersulfate, ceric ammonium, sodium hydroxide, and/or azo compounds(e.g., azobisisobutyronitrile).

In one embodiment, the initiator is used for a free radical reaction. Inanother embodiment, the initiator allows a terminal olefin on a monomerto generate a modified biopolymer. Exemplary monomers include, but arenot limited to, styrene, vinyl acetate, acrylic acid, acrylonitrile,butadiene, methyl methacrylate, butyl acrylate, acrylamide, and/ordiallyl dimethyl ammonium chloride.

In one embodiment, the initiator is present in the homogeneous reactionblend in an amount of about 1% to about 100% or more by weight of atleast one biopolymer present in the homogeneous reaction blend.

In one embodiment, the modified biopolymer is subjected to a foamingprocess. Foaming induces porosity and/or void size of the modifiedbiopolymer, such as by opening and/or increasing cell porosity.Additionally, foaming aids in increasing fluid, charged species, and/ormetal sequestration, binding, absorption, chelation, uptake and/or thelike. In another embodiment, the modified biopolymer has open, connectedpores, which facilitates mass transfer within the modified biopolymerand access of ions in a fluid to the ionic binding sites of the modifiedbiopolymer. In yet another embodiment, foaming the modified biopolymermodifies (e.g., increases or decreases) viscoelastic properties of themodified biopolymer. In still another embodiment, the amount or degreeof modification of the viscoelastic properties varies with the amount ofa fluid (e.g., water, carbon dioxide, nitrogen, etc.) absorbed in themodified biopolymer at the time of foaming.

A foaming agent is a chemical agent or a physical agent in oneembodiment. Exemplary foaming agents, include, but not are limited to,supercritical nitrogen (N₂), calcium carbonate (CaCO₃), water (e.g.,steam), and/or supercritical carbon dioxide (CO₂).

Optional additives used to prepare the modified biopolymer include, butare not limited to, dyes, pigments, organic fillers, inorganic fillers,softening agents (e.g., mineral oils and synthetic oils), flameretardants, crystallization accelerators, stabilizers (e.g., heat andlight stabilizers), tie-agents, nucleating agents, other polymers (e.g.,non-biopolymers), and/or the like.

In a preferred embodiment, an extruder is used to carry out thecharge-modification and/or the crosslinking reaction. Exemplary devicesfor carrying out a method of the present invention include, but are notlimited to, co-rotational and counter rotational twin screws, thermalkinetic compounders, high shear mixers, paddle mixers, static mixersblenders, open-type mixing mills, closed Banbury mixers, kneaders,single-screw extruders, vented screw extruders, and/or twin-screwextruders (e.g., a parallel or conical twin-screw extruders). FIGS. 6A,6B, and 6C illustrate examples of exemplary screw configurations. A lowshear screw configuration (FIG. 6A) includes a low number of or no shearinducing elements or zones along the screw profile. The shear inducingelements or zones include mixing, kneading, and/or reversing elements orzones which increase the torque or load on the extrusion motor for agiven mass flow rate. A medium (FIG. 6B) and/or high shear (FIG. 6C)screw configuration includes an increased number of shear inducingelements or zones compared to a low shear screw configuration.

The charge-modification and/or crosslinking reaction is preferablyperformed and/or carried out as a single-stage direct extrusion processor a multi-stage extrusion process. In one embodiment, thecharge-modification and/or crosslinking reaction includes in-linecompounding. In another embodiment, the charge-modification and/orcrosslinking reaction is carried out in an extruder with at least tworeaction zones and the at least two reaction zones are used for one ormore steps in the method for preparing the modified biopolymer. In oneexample, a biopolymer and at least one charge-modifying agent arereacted at a first reaction zone to form a charge-modified biopolymerand the charge-modified biopolymer is crosslinked at a second reactionzone to form a crosslinked, charge-modified biopolymer.

In one embodiment, the extruder is used as one complete reaction vessel,which allows for the reaction to occur along the entire length of theextruder. When two or more reaction zones are provided, the one or moreprocess conditions (e.g., temperature, shear, etc.) in at least onereaction zone are preferably independent of the one or more processconditions in another reaction zone. In one embodiment, a differenttemperature and/or screw element is provided in at least one reactionzone compared to another reaction zone. In one example, a mixture of abiopolymer (e.g., starch), a plasticizer, a charge-modifying agent, anda catalyst are introduced into a feed zone in an extruder to form ahomogeneous reaction blend in the extruder. Varying the temperature inone or more reaction zones in the extruder modifies (e.g., acceleratesand/or slows) the reaction taking place in the extruder. In oneembodiment, the reaction is accelerated by increasing the temperature inone or more reaction zones in the extruder. Additionally oralternatively, shear is introduced in one more reaction zones (e.g.,zone 3 and/or zone 5 of an extruder) by having intense mixing elementsin the screw to facilitate mixing and/or shear induced reaction. In yetanother embodiment, the length of different reaction zones and/or thelength of the extruder itself (e.g., by moving the injection zone closerto the end of the extruder) is varied or adjusted to modify the degreeof reaction. The length of the extruder is generally defined as a lengthover diameter ratio or L/D.

In one embodiment, the extruder is used as a sequential reactor. In oneexample, a mixture of a biopolymer (e.g., starch), a plasticizer, and acharge-modifying agent are introduced into a feed zone of an extruder.The mixture is heated as it is transported through one or more reactionzones (e.g., one or more initial reaction zones, such as, e.g., zones 1and 2) using conveying elements on the screw, and the charge-modifyingagent reacts with the biopolymer to form a charge-modified biopolymer.Then, a crosslinking agent is added in either solid or liquid form intoone or more reaction zones (e.g., zone 3) to form the crosslinked,charge-modified biopolymer. In another embodiment, following thereaction zone(s) in which the charge-modifying agent was added, anintense mixing screw element is placed on the screw in one or morereaction zones (e.g., in zone 4 and/or 5) to mix the crosslinking agentwith the charge-modified biopolymer. In yet another embodiment, thecrosslinking reaction is facilitated by different temperatures and/ordifferent screw elements in one or more reaction zones (e.g., zone 4and/or 5). In still another embodiment, a foaming agent (e.g., water) isinjected into the extruder (e.g., in a reaction zone near the end of theextruder, such as, e.g., at zone 6), which causes the crosslinked,charge-modified biopolymer to expand as it exits the die.

In one embodiment, one or more reagents (e.g., the biopolymer) is inpowder form when added to an extruder and is not in the form of a liquidor a paste. In another embodiment, the one or more reagents in powderform has a moisture content of about 20% by weight or less. In yetanother embodiment, the biopolymer and/or the charged-biopolymer areadded to the extruder in powder form and/or one or more additionalreagents (e.g., a charge-modifier, a plasticizer, a crosslinker, etc.)are added to the extruder in powder form. The one or more additionalreagents are added in the same or a different reaction zone than thebiopolymer and/or the charge-modified biopolymer.

In one embodiment, components or reactants for one or more steps are drymixed together prior to addition to the extruder. Alternately or inaddition, two or more feeders (e.g., loss-in-weight feeders) are usedthat supply the components or reactants to be blended to the extruder.In one embodiment, multiple extruders are used to feed melts of theblend components, such as in co-extrusion. The components, reactants,and/or mixture blends are optionally sized by conventional means such aspelletization, granulation, and/or grinding.

One or more process conditions are modified to provide a particularmodified biopolymer (e.g., a superabsorbent, ion exchange resin, etc.)and/or a particular property of a modified biopolymer (e.g., degree ofcharge modification, crosslinking, etc.). Example processing conditionsinclude, but are not limited to, the type of extruder (e.g., singlescrew vs. twin screw); screw diameter (D); screw length (L) (L/D isoften used to describe an extruder configuration); screw configuration(i.e., specific types of shear inducing sections within an extruderwhich may range from gentle conveying elements to more shear intensiveelements that may be designed to enhance uniform mixing within theextruder and/or accelerate a chemical reaction); temperature (overalland profile along various extruder zones); screw RPM; number of separateextruder zones where both temperature can be changed independent ofother zones and different ingredients of the formulation can be added;and feed rate of different formulation elements into different zones. Insome embodiments, the combination of one or more independentlycontrolled process variables influence dependent variables of residencetime, mechanical energy input (SME) and/or shear. Changes in screw RPMmay induce changes in shear, heating and/or residence time in theextruder.

The reacting and/or crosslinking step(s) are preferably carried outand/or performed in a homogeneous reaction blend. In a preferredembodiment, the reacting and/or crosslinking step(s) are carried outand/or performed using a reactive extrusion process. The reacting and/orcrosslinking step(s) are preferably carried out at a temperature thatavoids degradation of the biopolymer and/or the modified biopolymer.Advantageously, increasing the temperature of the reacting and/orcrosslinking steps provides for an increased amount ofcharge-modification on the biopolymer if the temperature remains belowthe degradation temperature for the biopolymer. In one embodiment, thereacting and/or crosslinking step(s) are carried out at a temperature ina range of about 80° C. to about 200° C. (e.g., at a temperature in arange of about 80° C. to about 120° C., about 80° C. to about 150° C.,about 90° C. to about 120° C., about 100° C. to about 120° C., about100° C. to about 200° C., about 150° C. to about 180° C., or about 110°C. to about 130° C.). In another embodiment, the reacting and/orcrosslinking step(s) are carried out at a temperature of about 140° C.or less. In a preferred embodiment, the reacting step is carried outand/or performed at a temperature in a range of about 100° C. to about175° C. (e.g., about 120° C. to about 140° C. or about 100° C. to 150°C.). In another preferred embodiment, the crosslinking steps are carriedout and/or performed at a temperature in a range of about 120° C. ormore (e.g., about 120° C. to about 175° C. or about 120° C. to about140° C.).

As previously described, the reacting and/or crosslinking step(s) arepreferably carried out in an extruder. In one embodiment, the reactingand/or crosslinking step(s) are carried out in an extruder with aresidence time in a range of about 0.1 minutes to about 30 minutes(e.g., in a range of about 0.1 minutes to about 10 minutes, about 0.5minutes to about 5 minutes, about 1 minute to about 10 minutes, about 1minute to about 5 minutes, or about 1 minute to about 3 minutes). Inanother embodiment, the reacting and/or crosslinking step(s) are carriedout in an extruder with a residence time of about 5 minutes. In yetanother embodiment, increasing the residence time of the reacting and/orcrosslinking step(s) provides for an increased amount ofcharge-modification on the biopolymer.

The extruder preferably has a screw RPM in a range of about 10 to about500 RPM (e.g., about 10 to about 200 RPM, about 50 to about 200 RPM,about 100 to about 200 RPM, about 125 to 250 RPM, about 100 to about 500RPM, or about 90 to about 130 RPM). In one embodiment, the reactingand/or crosslinking step(s) are carried out in an extruder having ascrew RPM of about 120 RPM.

The extruder preferably has a Specific Mechanical Energy (SME) value ofat least about 20 kJ/kg. In one embodiment, the extruder has a SME valuein a range of about 20 kJ/kg to about 500 kJ/kg or about 25 kJ/kg toabout 250 kJ/kg. The SME value may be measured using methods known tothose of skill in the art.

In one embodiment, the modified biopolymer is treated after formation(i.e., a post-treatment). An example of a post-treatment is thermallytreating a charge-modified biopolymer and/or crosslinked,charge-modified biopolymer post extrusion. In one embodiment, thepost-treatment increases the degree of crosslinking present in themodified biopolymer and/or increases and/or improves charge densityand/or charge modification of the modified biopolymer. In anotherembodiment, the post-treatment decreases a soluble gel fraction in themodified biopolymer. In yet another embodiment, the modified biopolymerin solid form undergoes a post-treatment. In still another embodiment,the post-treatment fine tunes and/or modifies the properties of themodified biopolymer.

In one embodiment, the post-treatment includes heating the modifiedbiopolymer. In another embodiment, the post-treatment includes heatingthe modified biopolymer at a temperature in a range of about 80° C. toabout 180° C. (e.g., about 100° C. to about 150° C. or about 120° C. toabout 140° C.) for a period of time in a range of about 0.5 minutes toabout 24 hours (e.g., about 5 minutes to about 180 minutes, or about 30minutes to about 90 minutes). In yet another embodiment, thepost-treatment includes heating the modified biopolymer at a temperatureof about 110° C. to about 130° C. for a period of time in a range ofabout 60 minutes to about 120 minutes. In still another embodiment, thepost-treatment includes heating the modified biopolymer at a temperatureof about 130° C. to about 150° C. for a period of time in a range ofabout 10 minutes to about 50 minutes.

Unreacted reagents, soluble and/or low molecular weight species, and/ordegradation products are preferably removed from the modified biopolymer(e.g., by rinsing, dialyzing, and/or the like the modified biopolymer).In one embodiment, unreacted reagents are removed from the modifiedbiopolymer after a post-treatment. In another embodiment, the modifiedbiopolymer is dried (e.g., at a temperature of about 40° C.).

In one embodiment, the modified biopolymer is further modified bygrinding, milling, pelletizing, drawing, compressing, shaping, and/orthe like to provide a formed modified biopolymer. The formed modifiedbiopolymer may be of any shape and/or size. In one embodiment, theformed modified biopolymer is of substantially uniform size and/or shape(e.g., varying in size and/or shape by less than about 20%). In anotherembodiment, the formed modified biopolymer consists of a variety ofparticle sizes and/or shapes. As used herein, particle size refers tothe diameter of particles. In yet another embodiment, the modifiedbiopolymer is in the form of a bead, column, sheet, powder, particle(e.g., nanoparticles, microparticles, etc.), ribbon, fiber, film,pellet, and/or the like. In still another embodiment, the modifiedbiopolymer is in the form of a particle having a diameter in a range ofabout 1 micron to 2,000 microns (e.g., in a range of about 10 microns toabout 1000 microns, about 100 microns to about 1000 microns or about 300to about 800 microns). In a preferred embodiment, the modifiedbiopolymer has a particle size in a range of about 300 to about 800microns or less than about 500 microns, which is preferable for use asan absorbent. In another preferred embodiment, the modified biopolymerhas a particle size in a range of about 10 to about 150 microns or lessthan about 100 microns, which is preferable for use as an ion exchangematerial.

In one embodiment, the modified biopolymer lacks a granular structureand/or morphology. In another embodiment, the modified biopolymer lacksa crystalline structure.

In one embodiment, forming the homogeneous reaction blend includes meltblending at least one biopolymer and at least one charge-modifyingagent, optionally with at least one plasticizer, a catalyst (e.g., aninitiator), and/or optional additives. In another embodiment, at leastone biopolymer, at least one charge-modifying agent, at least oneplasticizer, and optionally a catalyst are combined to form ahomogeneous reaction blend.

In one embodiment, a charge-modified starch is prepared and/or formed byforming a first homogeneous reaction blend in an extruder. Thecharge-modified starch is extruded and extrudate is optionally groundinto a powder and/or pelletized. In another embodiment, the extrudate isthen combined with chitosan, a plasticizer, and optionally a secondcharge-modifying agent to form a second homogeneous reaction blend.

In one embodiment, a homogeneous reaction blend is formed by combining astarch, at least one charge-modifying agent, optionally at least oneplasticizer, and optionally at least one catalyst. The starch and the atleast one charge-modifying agent are reacted to form a charge-modifiedstarch. In another embodiment, the at least one charge-modifying agentis an acid, the optional at least one plasticizer is water and/orglycerol, and/or the optional at least one catalyst is sodiumhypophosphite. In yet another embodiment, the reacting step includesreacting starch and the charge-modifying agent in a ratio in a range of0.1:1 to 4:1 (charge-modifying agent: starch) (e.g., in a ratio in arange of 0.5:1 to 2:1 or 1:1 to 3:1).

In one embodiment, the charge-modified starch is crosslinked withanother biopolymer, such as, for example, chitosan to form acrosslinked, charge-modified starch-chitosan. In another embodiment, thechitosan is charge-modified (e.g., protonated). In yet anotherembodiment, a charge-modified starch is combined with chitosan, at leastone plasticizer, and optionally a charge-modifying agent. Thecharge-modified starch and chitosan are then crosslinked. In stillanother embodiment, a charge-modifying agent is an acid (e.g., aceticacid) and reacts with chitosan to form charge-modified chitosan. In oneembodiment, the charge-modified chitosan is crosslinked with thecharge-modified starch. In another embodiment, charge-modified chitosanis prepared by reacting chitosan and acetic acid in amount of about 1%to about 40% by weight of the chitosan (e.g., about 2.5% to about 13% orabout 20% to about 40% by weight of the chitosan). Acetic acid ispreferably added directly to the chitosan without the presence of water.

In one embodiment, the modified biopolymer is used as and/or to prepareconsumer products, such as, but not limited to, diapers, hygieneproducts including feminine hygiene products, and/or a wound dressing.In another embodiment, the modified biopolymer is used as and/or toprepare an ion exchange resin and/or an absorbent. Thus, in oneembodiment, the modified biopolymer is an ion exchange resin, ionremoval resin, metal chelating and/or adsorbing resin, and/or anabsorbent, including high performing absorbents (e.g., asuperabsorbent). In yet another embodiment, the modified biopolymerremoves contaminants from a fluid and/or absorb a fluid.

Further exemplary industries and/or uses for the modified biopolymerinclude, but are not limited to, water treatment, such as, for example,single-use ion exchange for water deionization (e.g., for laboratoriesand/or electronics), potable water desalination, potable watercontaminant and heavy metals adsorbents, and an alternative to activatedcarbon for dechlorination; hygienic superabsorbent polymer (SAP)applications, such as, for example, baby diaper absorbents, adultincontinence absorbents, feminine hygiene absorbents; non-hygienic SAPapplications such as, for example, sub-sea cable wraps, re-usablegel/ice packs, liquid waste solidification, pet pads, meat pads,concrete additives, removal of water from oil and/or hydrocarbons,liquid/solid separation, waste lagoon remediation, paint solidification,agricultural and horticultural soil amendments, mortuary absorbents,whole blood or blood mixture absorbents, medical waste solidificationand spill control, drug delivery systems, and wound dressings; energy,such as, for example, hydraulic fracturing flowback water treatment orreuse, guar alternative hydraulic fracturing viscosifying agent,hydraulic fracturing friction reducer additive, lost circulationdrilling fluid additive, oil refinery water treatment, cooling towerwater softening, boiler feed water deionization, coal ash and flu ventremediation, and nuclear isotope removal; mining, such as, for example,metals mining water treatment, metal removal from mining solutions, andcoal mining water treatment; environmental, such as, for example, pumpand treat water remediation, in situ reactive barrier remediation, andsludge absorption and dewatering; packaging, such as, for example,biobased packaging films and biobased structural packaging; paper suchas, for example, pulp and paper strength additives and/or coatings forpaper; textiles such as, for example, textile adhesives, starch esteralternative for textile manufacture, and textile non-woven thickeningagents; and/or construction, such as, for example, construction adhesiveand/or binder in wallboard. In one embodiment, the modified biopolymeris useful in the paper industry, cosmetics, tissue engineering,hydrogels, drug delivery applications, or photonics applications. Inanother embodiment, the modified biopolymer is used as a flocculantand/or a coagulant.

In a preferred embodiment, the modified biopolymer is a superabsorbentthat is incorporated into an absorbent hygiene article (e.g., diaper,incontinence product, feminine hygiene product, wound dressing) used toabsorb one or more bodily fluids (e.g., urine, blood, feces, menses). Ingeneral, absorbent hygiene articles are constructed with a top layer(e.g., a topsheet layer), a back layer (e.g., a backsheet), and anabsorbent core, wherein the absorbent core is located between the toplayer and the back layer. In one embodiment, the absorbent core isattached to the top layer and/or the back layer via physical,mechanical, or chemical means. For example, in one embodiment, theabsorbent core is attached to the top layer, the back layer, or anyintermediate layers via an adhesive. In another embodiment, theabsorbent core is attached to the top layer, the back layer, or anyintermediate layers directly via stitched, woven, or other method oftextile construction.

Structures are, in one embodiment, similar or identical to that ofconventional hygiene products yet have the benefits of the materials andelements disclosed herein that provide biocompostability with improvedperformance and biodegradability compared to prior attempts atbiodegradable hygienic articles. Examples of conventional products canbe found described in U.S. Pat. No. 9,913,763, to inventors Ryu, et al.,which is incorporated herein by reference in its entirety, and whichdiscloses absorbent articles including a liquid-permeable topsheet, aliquid-impermeable backsheet, and an absorbent core located between saidtopsheet and said backsheet. Another example of a conventional productcan be found described in U.S. patent application Ser. No. 15/309,658,to inventors Yu, et al., which is incorporated herein by reference inits entirety, and which discloses an absorbent article with a fluidacquisition layer being positioned between the body facing liner and thebacksheet.

The top layer (e.g., topsheet) is the part of the absorbent hygienearticle that comes in contact with a wearer's body (e.g., skin, hair).Notably, the top layer is referred to as the topsheet, topsheet layer,top layer, or uppermost layer and is preferably a non-woven layer. Thetopsheet is designed to allow fluids (e.g., urine, menses) to penetratethrough the topsheet and aids in wicking moisture through the article tothe absorbent core. The topsheet is generally formed from materialsincluding, but not limited to, at least one woven material, at least onenonwoven material, at least one natural fiber, and/or at least onesynthetic fiber, wherein the topsheet is produced via mechanical,chemical, or thermal means. In one embodiment, the topsheet is incontact with and/or is attached to at least one intermediate sheet, suchas a transfer layer or an acquisition distribution layer (ADL), whereinthe intermediate sheet provides a low-density layer that improveswicking performance. The intermediate layer further improvesdistribution of fluid within the non-woven core such that fluid isdispersed evenly and/or advantageously across an absorbent core.Advantageous dispersion of fluid, in one embodiment, includesdistribution of the fluid to outer areas of an absorbent core, forexample via physical structures such as pores, channels, creases, orvarying textures. In another embodiment, the advantageous dispersion offluid includes distribution of the fluid to outer areas and/or to inneror deeper layers of the absorbent core, for example, via physicalstructures such as pores, channels, creases, or varying textures. In oneembodiment, the topsheet, any intermediate layers, and/or the absorbentcore are sectionalized or embossed, wherein the absorbent core isconstructed and arranged in patterns and shapes (e.g., embossed patternsand shapes) that draw moisture through the hygienic article in adistributed manner, such as compartmentalized triangles, squares,circles, or any variety of linear patterns. In one embodiment, the toplayer is constructed from absorbent material and/or is integrated withthe absorbent core, wherein the top layer is constructed from abiodegradable polymer. In another embodiment, the topsheet isconstructed with the biodegradable materials described herein (e.g.,including a biocompostable SAP) and is integrated within a hygienicmaterial similar to the product described in U.S. patent applicationSer. No. 15/369,886 to inventor Sookraj, which is incorporated herein byreference in its entirety. In one embodiment, the topsheet isimpregnated with an SAP, wherein the SAP is dispersed within thetopsheet. Additionally, the topsheet is operable to retain SAP particlesvia an outer and/or inner layer, wherein the outer and/or inner layerforms a void within the topsheet, and wherein the topsheet is optionallyfilled with an absorbent material, such as wood pulp fibers, cellulosefluff, or any other absorbent material known in the art of hygienicarticles. The outer and/or inner layers are preferably constructed froma same material and are porous to allow wicking of moisture to the ADLand/or the absorbent core. In another embodiment, the topsheet, the ADL,the absorbent core, and/or any other layers include one or moreintegrated hygienic or aesthetic gels, oils, lotions, creams, or otherfluid, such as antibiotic ointments, moisturizers, anti-odor agents,and/or scented products.

In one embodiment, intermediate layers have a higher absorbency thanthose used in traditional, non-biodegradable disposable diapers. Forexample, in one embodiment, an ADL has a high to medium absorbency,wherein the high absorbency is combined with an SAP that has a lowerabsorbency than traditional SAPs used in hygiene products. In anotherembodiment, the ADL is constructed with multiple sub-layers, wherein atleast one layer of the ADL is operable to absorb fluid, and wherein atleast one second layer of the ADL is operable to wick and distributefluid across the absorbent article.

The ADL is, in one embodiment, constructed from non-woven materials,such as polypropylene, polyethylene, polyethylene terephthalate, or anyother standard synthetic used in ADL construction. In anotherembodiment, the ADL is constructed from woven or non-woven biodegradableor biocompostable materials, including cotton, silk, wool, cellulose, orhemp. For example, in one embodiment, the ADL is constructed frombiocompostable wool similar to the materials produced from the processdescribed in U.S. patent application Ser. No. 15/562,983, to inventorsHodgson, et al., for Wool treatment process and products, which isincorporated by reference herein in its entirety. In another embodiment,the ADL is constructed with properties similar to those described inU.S. patent application Ser. No. 15/778,842 to inventors Jackson, etal., which is incorporated by reference herein in its entirety and whichdescribes an acquisition distribution laminate.

Additionally and alternatively, the absorbent article includes a surgelayer, as described in U.S. patent application Ser. No. 16/095,403, toinventors Park et al., which is incorporated herein by reference in itsentirety, wherein the surge layer rapidly accepts and temporarily holdsthe liquid prior to releasing the liquid into, for instance, the fluidintake layer and/or the absorbent core. In another embodiment, theabsorbent article includes an absorbent layer between a topsheet and anintermediate layer (e.g., an ADL) and includes an absorbent core beneaththe intermediate layer, wherein the absorbent core includes asuperabsorbent polymer.

In one embodiment, the topsheet and/or the intermediate layers includean evenly distributed superabsorbent polymer (SAP). In anotherembodiment, the SAP is distributed such that an outer section of thehygienic absorbent article includes a lower concentration of SAP than aninner section. In one embodiment, the SAP is distributed in channels,patterns (e.g., circles, ellipses, lines, rectangles, triangles), and/orany other ideal distribution that provides ideal absorption (e.g.,anatomic distribution). In one embodiment, the absorbent articleincludes both a biocompostable SAP and a non-biocompostable SAP, whereinthe biocompostable SAP is distributed towards an outer region of theabsorbent core, and wherein the non-biocompostable SAP is distributedtowards an inner region of the absorbent core. Preferably, the total SAPdistribution is approximately uniform across the absorbent core. Inanother embodiment, the biocompostable SAP and the non-biocompostableSAP are arranged and integrated within the absorbent core in channels,patterns, and/or shapes in alternating, connected, and/or mixed manner.Alternatively, the biocompostable SAP has a higher distribution towardsan inner region of the absorbent core, and a non-biocompostable SAP hasa lower distribution towards an outer region of the absorbent core.

In one embodiment, the SAP includes evenly distributed pores throughoutthe polymer. Preferably, the SAP includes pores that are approximatelyequal in size. In another embodiment, the SAP includes pores that arerandomly distributed. In a further embodiment, the pores are random insize.

In another embodiment, pore size and fiber length of the absorbent corevaries according to the material and construction used in addition tothe SAP. In one embodiment, the absorbent core is non-porous.

In one embodiment, the absorbent core is constructed from an absorbentmaterial (e.g., fluff or other fibers) and a superabsorbent polymer. Inanother embodiment, the absorbent core includes an absorbent material, asuperabsorbent polymer, and/or one or more intermediate layers thatcontain the absorbent materials, wick fluid across the absorbentmaterials, and/or provide surge or additional absorbency in the article.The core is, in one embodiment, constructed with two cores, wherein thecores are positioned laterally, and wherein the cores form a centralchannel that wicks fluid. In another embodiment, two or more cores arepositioned in patterns and shapes to improve absorbency in area and/orto improve fluid acquisition and distribution (e.g., through theformation of channels). In another embodiment, the cores are stacked,wherein channels, intermediate layers, and/or air space providesimproved acquisition, distribution, and absorbency. In a furtherembodiment, the absorbent core is folded one or more times. For example,the core is folded into thirds, wherein the absorbent core forms acentral, longitudinal channel. In another embodiment, the core is foldedonto itself in a symmetrical or asymmetrical manner, and wherein thecore forms a multi-layer core. For example, a left and a right side ofthe core are each folded multiple times symmetrically upon itself toform a three or six layer core. In another embodiment, the core isfolded in half one or more times to create a multi-layer core.Additional folded constructions for an absorbent core can be found inU.S. patent application Ser. No. 14/634,718, to inventors Chmielewski,et al, which is incorporated herein by reference in its entirety.Notably, each of these core constructions include a superabsorbentpolymer that is integrated, contained, and/or layered above, on, and/orwithin the absorbent core, wherein the superabsorbent polymer ispreferably biocompostable and/or biodegradable.

The backsheet prevents fluids (e.g., urine, menses) from passing throughthe absorbent hygiene article and leaking (e.g., onto clothing, skin,etc.). The backsheet is formed from materials including, but not limitedto, at least one woven material, at least one nonwoven material, and/ora polymeric and/or a thermoplastic film (e.g., polyethylene,polypropylene). In one embodiment, one or more of the at least onenonwoven material is a film-coated nonwoven material. The backsheet isgenerally designed to allow water vapor and air to permeate (i.e.,“breathable”) without allowing fluids to pass through the backsheet. Inone embodiment, the backsheet is attached to the topsheet via, forexample, an adhesive, stitching, or any other mechanical, physical, orchemical means known in the art. In another embodiment, the absorbentcore is attached to the backsheet via any similar mechanical, physical,or chemical means.

The absorbent core absorbs and traps the fluids. The absorbent core isformed from materials including, but not limited to, cellulose fluffpulp, wood pulp fibers, and/or at least one superabsorbent material. Inone embodiment, these materials are constructed into a core matrix,wherein the core matrix comprises a network of fibers, and wherein thefibers are constructed from natural or synthetic material. The absorbentcore is, in one embodiment, constructed with a natural fluff material,such as cellulose fluff or cotton. In another embodiment, the absorbentcore is constructed with synthetic fluff material, such as polyester,polyethylene, or polypropylene. In a further embodiment, the core matrixis constructed from “fluffless” or alternative non-woven materials,including a web of airlaid fabric with natural or synthetic materials,which is often used in feminine hygiene products. In one embodiment, theairlaid fabric is similar to the materials disclosed in U.S. Pat. No.5,445,777 to inventor Noel, et al., which is incorporated herein byreference in its entirety. In one embodiment, the core matrix is atleast approximately 50% airlaid fabric. In another embodiment, the corematrix is at least approximately 65% airlaid fabric. In a furtherembodiment, the core matrix is at least approximately 85% airlaidfabric. In yet another embodiment, the core matrix is between 50% and100% airlaid fabric, wherein between 0% and 50% of the core matrixincludes an adhesive, a bonding agent, and/or a superabsorbent polymer.Bonding agents in one embodiment include resins, latex emulsions, and/orthermoplastic fibers.

“Curly” fibers are also considered as components of a fluffless coreaccording to one embodiment of the present invention. Curly fibers aremodified cellulose fibers, and are described in U.S. Pat. No. 6,780,201to inventors Sun et al., which is incorporated herein by reference inits entirety.

In one embodiment, the topsheet, the backsheet, the absorbent core,and/or any intermediate layers are constructed from viscose, includingfibers derived from wood pulp, bamboo, cotton, wool, silk, or anysynthetic materials, including nylon, polyester. In another embodiment,the layers are constructed from rayon, spandex, Modal, or Micromodalmaterial.

Preferably, the SAP is integrated into absorbent and distributingmaterial, wherein the core is constructed with pores and channels thatboth trap any received fluid and direct the fluid to SAP particles. In apreferred embodiment, the article includes wood pulp fibers withdistributed superabsorbent materials. In one embodiment, the absorbentcore includes at least one absorbent foam (e.g., polyurethane foam, highinternal phase emulsion (HIPE) foam). Preferably, the absorbent core isbiodegradable, compostable, and/or recyclable. In one embodiment, theabsorbent core includes absorbent and/or barrier layers between asuperabsorbent material. Particle sizes of the superabsorbent materialsare important to comfort, wherein a size, distribution, and shape of theparticles affect the article perceived softness and the point at which afluid is felt before an absorbent core is saturated. For example, a sizeof the particle is preferably hard enough to have sufficient structurewithout allowing any fluid to be felt by a wearer until the article isbetween 90% and 100% saturated. In one embodiment, the particle sizesare between approximately 100 and 850 micrometers. In anotherembodiment, the particle sizes are between approximately 150 and 650micrometers. In one embodiment, at least 50% of the particle sizes arebetween 100 and 850 micrometers. In another embodiment, at least 85% ofthe particle sizes are between 100 and 850 micrometers. In yet anotherembodiment, at least 85% of the particle sizes are between 100 and 650micrometers. In another embodiment, at least about 99.5% of the particlesizes are between 150 to 850 micrometers, with about 30% to about 35% ofthe particles being between about 500 micrometers to about 850micrometers, about 25% to about 30% of the particles being between about350 micrometers to about 500 micrometers, and about 150 micrometers toabout 355 micrometers.

Particle sizes balance gel strength with absorption. For example, alarge particle size generally corresponds to a high gel strength but alow rate of absorption, whereas a small particle size generallycorresponds to a lower gel strength but a higher rate of absorption.

In another embodiment, SAPs of the present invention are combined withnon-biodegradable, non-biocompostable, non-biorenewable, and/ornon-recyclable SAPs. In one embodiment, biodegradable, biocompostable,biorenewable, and/or recyclable SAPs are between 10% and 100% of theSAPs used. In another embodiment, they are between 25% and 75% of theSAPs used. In yet another embodiment, they are between approximately 25%and approximately 40% of the SAPs used. In other embodiments, they arebetween approximately 30% to 40% of the SAPs used. In a furtherembodiment, they are approximately 50% of the SAPs used. In yet anotherembodiment, biodegradable, biocompostable, biorenewable, and/orrecyclable SAPs make up between approximately 20% and 30% of the totalSAPs in the absorbent core of the absorbent article. However, thebiodegradable, biocompostable, biorenewable, and/or recyclable SAPs areoperable to be any percentage of the SAPs in the core by weight,depending on the application of the core including the SAP. However, ina preferred embodiment, the biodegradable, biocompostable, biorenewable,and/or recyclable SAP is 100% of the SAP utilized in the absorbent core.In one embodiment where 100% of the SAP utilized in the absorbent coreis the biodegradable, biocompostable, biorenewable, and/or recyclableSAP, weights of between 12 and 20 grams of the SAP are included in theabsorbent core. Alternatively, between 10 to 25 grams of the SAP areincluded in the absorbent core. These embodiments, and all otherembodiments recited in the present specification, assume a traditionalsize 4 baby diaper. Modifications to the weight of SAP included in thecore are operable to be adjusted depending on other applications, suchas for sizes P, N, 1, 2, 3, 5, 6, and 7 baby diapers. In otherembodiments, between 6 grams and 12 grams of the SAP are included in theabsorbent core. Biodegradable, biocompostable, biorenewable, and/orrecyclable SAPs are, in one embodiment, distributed towards an outer oran inner section of the absorbent core. In another embodiment, thebiodegradable, biocompostable, biorenewable, and/or recyclable SAPs areincluded in a secondary absorbent core layer, wherein the secondaryabsorbent core is positioned above or below a first absorbent core, andwherein the first absorbent core includes a non-biodegradable,non-biocompostable, non-biorenewable, and/or a non-recyclable SAP. Inone embodiment, the absorbent cores are attached mechanically,physically, or chemically, such as through stitching, weaving, pinning,adhering, or any other method of attachment known in the art of hygienicproducts. In one embodiment, intermediate layers are positioned betweena secondary and a first absorbent core, wherein the intermediate layersaid in wicking fluid between each of the cores according to anabsorbency rate of each of the SAPs or cores as a whole. In anotherembodiment, the intermediate layers separate and/or surround theabsorbent cores, wherein SAPs between a secondary and first core areprevented from mixing and/or interacting.

Mixtures of SAPs exhibit increased biodegradability with modifiedperformance metrics. For example, in one acquisition time under load(ATUL) embodiment, a mixture of 25% biocompostable SAP (any of themodified biopolymers described in Examples 11-12 below) and 75%non-biocompostable SAP exhibits an acquisition time between 50 and 200seconds for each of three equal dosing volumes of 0.9 wt % salinesolution between 75 ml and 85 ml, and a rewet absorbency exhibitsbetween 0% and 25% residual/release uptake of the dosing volume for eachof the three doses. Rewet under load according to the present inventionis performed at 0.70 psi. In another embodiment, a mixture of 50%biocompostable SAP (any of the modified biopolymers described inExamples 11-12 below) and 50% non-biocompostable SAP exhibits anacquisition time between 50 and 250 seconds for each of three dosingvolumes between 75 ml and 85 ml, and a rewet absorbency exhibits between0% and 50% residual/release uptake of the dosing volume for each of thethree doses. In another embodiment, the biodegradable SAP alone exhibitsan acquisition time between 50 and 500 for each of three dosing volumesbetween 75 ml and 85 ml, and a rewet absorbency exhibits between 0% and75% residual/release uptake of the dosing volume for each of the threedoses.

In another ATUL embodiment, a mixture of 25% biocompostable SAP (any ofthe modified biopolymers described in Examples 11-12 below) and 75%non-biocompostable SAP exhibits an acquisition time between 50 and 200seconds for each of three equal dosing volumes between 75 ml and 85 ml,and a rewet absorbency exhibits between 0% and 5%, between 0% and 5%,and between 0% and 25% residual/release uptake of the dosing volume foreach of the three doses, respectively. In another embodiment, a mixtureof 50% biocompostable SAP (any of the modified biopolymers described inExamples 11-12 below) and 50% non-biocompostable SAP exhibits anacquisition time between 50 and 250 seconds for each of three dosingvolumes between 75 ml and 85 ml, and a rewet absorbency exhibits between0% and 5%, between 0% and 10%, and between 0% and 50% residual/releaseuptake of the dosing volume for each of the three doses, respectively.In another embodiment, the biodegradable SAP alone exhibits anacquisition time between 50 and 500 for each of three dosing volumesbetween 75 ml and 85 ml, and a rewet absorbency exhibits between 0% and5%, between 0% and 25%, and between 0% and 75% residual/release uptakeof the dosing volume for each of the three doses, respectively.

In another ATUL embodiment, a mixture of 25% biocompostable SAP (any ofthe modified biopolymers described in Examples 11-12 below) and 75%non-biocompostable SAP exhibits an acquisition time between 50 and 200seconds for each of three equal dosing volumes between 75 ml and 85 ml,and a rewet absorbency exhibits between Oml and 5 ml, between Oml and 5ml, and between Oml and 22 ml residual/release uptake of the dosingvolume for each of the three doses, respectively. In another embodiment,a mixture of 50% biocompostable SAP (any of the modified biopolymersdescribed in Examples 11-12 below) and 50% non-biocompostable SAPexhibits an acquisition time between 50 and 250 seconds for each ofthree dosing volumes between 75 ml and 85 ml, and a rewet absorbencyexhibits between Oml and 5 ml, between Oml and 10 ml, and between Omland 30 ml residual/release uptake of the dosing volume for each of thethree doses, respectively. In another embodiment, the biodegradable SAPalone exhibits an acquisition time between 50 and 500 for each of threedosing volumes between 75 ml and 85 ml, and a rewet absorbency exhibitsbetween Oml and 5 ml, between Oml and 22 ml, and between Oml and 65 mlresidual/release uptake of the dosing volume for each of the threedoses, respectively.

In one embodiment, the acquisition time is approximately within +/−10seconds of Table A1, wherein each row of the chart corresponds to adosing volume of 80 ml of 0.9 wt % saline. In another embodiment, theacquisition time is approximately equal to the data identified in FIG.11A, wherein each column of the graph corresponds to a dosing volume of80 ml of 0.9 wt % saline for a first, second, and third dose,respectively, for each combination of biocompostable andnon-biocompostable SAP. In one embodiment, the non-biodegradable SAP inFIG. 11A, in TABLE A1, or in any of the above mixture examples has a CRCof 34 and an AUL of 23.

TABLE A1 Acquisition Time Under Load (ATUL) 25% 50% 100% Biocom- Biocom-Biocom- postable SAP postable SAP postable SAP Dose 1 70 70 70Acquisition Time (s) Dose 2 95 95 120 Acquisition Time (s) Dose 3 165195 490 Acquisition Time (s)

FIG. 11B illustrates a comparison of saline absorbency at 30 minutes and2 minutes for blends of non-biocompostable and biocompostable SAPs (anyof the modified biopolymers described in Examples 11-12 below). In oneembodiment, the absorption and retention is approximately within +/−5grams of TABLE A2 and TABLE A3 below.

TABLE A2 Absorption and Retention (2 minutes) 50% Biocompostable 100%Biocompostable SAP SAP Saline Absorbed (g) 595 550 Saline Retained (g)430 365

TABLE A3 Absorption and Retention (30 minutes) 50% Biocompostable 100%Biocompostable SAP SAP Saline Absorbed (g) 710 570 Saline Retained (g)495 360

In one embodiment, absorption capacity of a baby diaper productcontaining a biocompostable SAP (any of the modified biopolymersdescribed in Examples 11-12 below) submerged in approximately 0.9 wt %saline solution over 30 minutes is between approximately 500 ml and 800ml.

The above ATUL and absorbency examples are, in one embodiment, exhibitedin samples including an absorbent core with a total of 12 grams of SAPand 10 grams of wood pulp fluff and/or approximately a 55:45 ratio ofSAP to fluff material as well as a non-woven film of approximately 25gsm (grams per square meter), wherein an overall density of theabsorbent core is approximately 0.2 g/cm³. Rewet absorbency of theresidual/release is preferably measured with filter paper.

In one embodiment, a biocompostable SAP has a maximum absorbency that isbetween 70% and 115% of a non-biocompostable SAP alone. In anotherembodiment, a mixture of 50% biocompostable SAP and 50%non-biocompostable SAP has a maximum absorbency that is between 80% and115% of the non-biocompostable SAP alone. In one embodiment, theabsorbency of the biocompostable SAP is less than or equal to that ofthe non-biocompostable SAP, yet the biocompostable SAP is operable toreach maximum capacity in a shorter range of time compared to thenon-biocompostable SAP.

In one embodiment, a core used in the above examples was formed from acombination of wood pulp fluff and superabsorbent powder and wasapproximately 10 cm by 40 cm. The core was constructed and tested viathe following procedures. A core former provided a vacuum ofapproximately 3 inches H₂O (approximately 0.108 psi) and created airflow through a rectangular chamber to form cores on a screen that wereapproximately 10 cm by 40 cm. A bristle brush was used to feed wood pulpfluff and the superabsorbent powder through a screen at an end of thecore former to create a fine mix of wood pulp fluff and superabsorbentpowder. Approximately six (6) additions of the superabsorbent and fluffmixture were added to the core former. In one embodiment, the ratio ofsuperabsorbent to fluff is approximately 12 g of superabsorbent to 10 gof fluff. In another embodiment, the ratio of superabsorbent to fluff isapproximately 55:45. Alternatively, the ratio of superabsorbent polymerto fluff is approximately 60% to approximately 40%. In otherembodiments, the ratio of superabsorbent polymer in the absorbent coreto fluff is approximately 45% to approximately 70% SAP to approximately55% to approximately 30% fluff. In another embodiment, the core includes80% SAP to 20% fluff. Other embodiments include fluffless cores, whereina SAP is integrated with plastic-based nonwovens such as polyethylene orpolypropylene nonwovens. Resulting core material was deposited on anonwoven film on a top of the screen. The non-woven used in these testswere approximately 25 g/m². After a core was formed, it was mechanicallypressed (e.g., via a CLICKER PRESS). The resulting core wasapproximately 0.2 g/cm³. The cores of the above tests were placed incommercially available chassis, including a backsheet, topsheet, and anyintermediate layers (e.g., an ADL), wherein a core of the commerciallyavailable chassis was removed. All layers except for an originalabsorbent core remained in place and/or were reattached and/orre-adhered.

Absorption capacity of the above disclosed product was determined bysubmerging the fully assembled absorbent article in 0.9 wt % salinesolution for 30 minutes. The absorbent article was then removed andallowed to drain for 5 minutes before being weighed. The absorptioncapacity was calculated by subtracting a dry weight of the absorbentarticle from a wet weight of the absorbent article. After a wet weightwas measured, the wet absorbent article was placed into a vacuum box andcovered with a thin rubber bladder. The article was compressed with apressure of 14.5 inches of water (0.5233 psi) for 10 minutes, whichremoved any loose water from the article. The absorbent was article wasagain weighed to determine the retention weight, and the retentioncapacity was calculated by subtracting the dry weight of the diaper fromthe retention weight.

Acquisition time and rewet of the above disclosed product was determinedby forming the product into a curved shape by attaching forward and reartabs of the article together, resulting in a shape that mimicked theproduct in use. The absorbent article was placed in a plastic bowl forstabilization. 80 mL of 0.9 wt % saline was supplied to an insideabsorbent region of the diaper via a 4.7 cm inner diameter tube.Alternatively, 100 mL of 0.9 wt % saline is supplied to an insideabsorbent region of the diaper via a 4.7 cm inner diameter tube.Acquisition time was determined by an amount of time elapsed betweenwhen supply was initiated and when fluid from the tube was completelyabsorbed. After determining acquisition time, the tube was removed, andthe diaper was allowed to rest for 10 minutes. Multiple sheets of dryfilter paper were placed on the absorbent region of the product for 2minutes and a weight rested on the filter paper, resulting in a pressureof approximately 0.7 psi. The sheets of filter paper were removed andweighed, and rewet was calculated by subtracting the dry weight of thesheets of filter paper from the wet weight of the sheets of filterpaper. The acquisition time and rewet tests were repeated twice morewith a dose of 80 ml of 0.9 wt % saline.

In one embodiment, the absorbent core and/or any other secondary coresor intermediate layers are removable, such that a biodegradable,biocompostable, and/or recyclable core is easily removed from thehygienic article. For example, in one embodiment, the absorbent core isremovably attached, adhered, and/or retained to a top layer, wherein thetop layer is openable or removable, and wherein the absorbent core isoperable to be removed independently or in conjunction with the otherlayers. In another embodiment, the absorbent core is operable to beinserted into at least one sleeve, at least one pouch, and/or at leastone retaining element, wherein the absorbent core is easily removable.In a further embodiment, the topsheet, the absorbent core, and/or one ormore intermediate layers are attached, adhered, or retained as a singleremovable piece. For example, in one embodiment, the absorbent core isremovable, wherein an elastic retaining element holds a removableabsorbent core by corners or edges of the absorbent core.

As previously described, the absorbent core preferably includes at leastone superabsorbent material. The at least one superabsorbent material isa poly(meth)acrylate, a polyacrylamide, and/or a modified biopolymer asdescribed herein. In one embodiment, the at least one superabsorbentmaterial includes at least 5%, at least 10%, at least 15%, at least 20%,at least 25%, at least 30%, at least 40%, at least 50%, at least 60%, atleast 70%, at least 80%, or at least 90% of a modified biopolymer. Themodified biopolymer advantageously allows for the hygienic article to bebiodegradable, biocompostable, recyclable, and/or environmentallyfriendly with increased performance compared to previous articles thatare biodegradable.

In one embodiment, the absorbent hygiene article includes at least onefastener. In one embodiment, the at least one fastener includes hooktape and/or loop tape. In another embodiment, the at least one fastenerincludes at least one adhesive. In one embodiment, the at least oneadhesive is protected with a removable paper prior to use. In yetanother embodiment, the absorbent hygiene article includes wings (e.g.,menstrual pad) or side cuffs (e.g., diaper).

Preferably, the absorbent hygiene article includes at least one elementthat is biodegradable, compostable, and/or recyclable, wherein the atleast the absorbent core is biodegradable, compostable, and/orrecyclable. In one embodiment, the absorbent core is biodegradable byway of being constructed with bioderived polymers that are easily brokendown by natural biodegradable or compostable processes, such asbacterial anaerobic or aerobic digestion, and wherein byproducts of thebreakdown processes are non-toxic to humans. The absorbent coreincludes, in one embodiment, biocompostable elements, wherein theelements of the absorbent core meet ASTM standards forbiocompostability, such as biocompostability as tested according to ASTM5338, wherein 90% of the polymer in the absorbent core degrades within180 days in standard aerobic composting conditions. In anotherembodiment, the absorbent core is between 60% and 100% biocompostable.In another embodiment, each element of the hygiene article isbiocompostable according to a similar range as the absorbent core. In afurther embodiment, each element of the hygiene article isbiocompostable except for a backsheet and/or adhesive or liquidimpermeable materials. Whereas in the prior art, biodegradability wasnot feasible due in part to inefficiencies in materials and economicnon-viability, the claimed invention advantageously integrates thebiodegradable material disclosed above into a hygienic article withfurther biodegradable, compostable, and/or recyclable elements to ensurean environmentally friendly product that will disintegrate intonon-toxic products.

In an alternative embodiment, the biodegradable and biobased SAP of thepresent application is integrated into feminine hygiene products, suchas those described in U.S. application Ser. No. 17/038,954, filed Sep.30, 2020, which is hereby incorporated by reference herein in itsentirety. Other feminine hygiene applications include, by way of exampleand not limitation, tampons. For example, in one embodiment, a tamponincludes an outer wicking layer and a core impregnated with an SAP,including a biocompostable SAP as disclosed herein. In anotherembodiment, the hygienic article is an alternative feminine incontinenceproduct, such as a fin, as described in U.S. Pat. No. 10,143,772 toinventor Berryman, which is incorporated herein by reference in itsentirety, and wherein the feminine incontinence product includes abiocompostable SAP as disclosed herein. Alternatively, the hygienicarticle includes a biodegradable tampliner. In other embodiments, thehygienic article includes wound care products such as biodegradablewound care dressings including a protective backing, an absorbent corewith an integrated SAP, a nonwoven layer, and a wound contact layer. Inyet another embodiment, the present invention includes a BUTTERFLY® bodyliner or similar product including long wings or tabs extending from anabsorbent core including a SAP, with the absorbent core includingbiodegradable adhesive around the absorbent core.

FIG. 12 illustrates one embodiment of a layer distribution for thehygienic article, including a topsheet 901, an acquisition/distributionlayer (ADL) 903, an absorbent core 905, and a backsheet 907. Theabsorbent core 905 preferably is impregnated with SAP particles forincreased absorption. Advantageously, an absorbent core 905 includes atleast a biocompostable and/or biodegradable SAP. In another embodiment,the absorbent core 905, includes biodegradable and/or biocompostablefluff and/or additional layers. In an alternative embodiment, thetopsheet 901, the backsheet 907, and/or any intermediate layers arebiodegradable, biocompostable, and/or recyclable.

FIG. 13 illustrates on embodiment of a baby diaper 1001 including anabsorbent area 1003, wherein the baby diaper 1001 is constructed witheach the layers illustrated in FIG. 12. In one embodiment, the babydiaper 1001 does not include an ADL layer but only includes a topsheet,absorbent core with SAP particles, and a backsheet. In anotherembodiment, the diaper is modified for application to adult incontinenceproducts. For example, the absorbent area 1003 is constructed with asmaller shape and is anatomically contoured to female or male genitaliaand junctional areas.

FIG. 14 illustrates one embodiment of a female hygienic pad 1101 formenstrual hygiene, wherein the pad is constructed with a backsheet 1103,topsheet 1105, and absorbent core 1107 (demonstrated by hidden lines),wherein the absorbent core 1107 is positioned between the backsheet 1103and topsheet 1105. In one embodiment, a rear of the hygienic pad 1101includes an adhesive for attachment to a clothing article. Preferably,the adhesive is biodegradable, compostable, and/or recyclable, such as asoy or starch-based adhesive.

FIG. 15 illustrates another embodiment of an incontinence article 1201,wherein the incontinence article includes a topsheet 1203 and anabsorbent core 1205. In this embodiment, the incontinence article 1201does not include an acquisition distribution layer. The absorbent coreis, in one embodiment, constructed with fluff and includes abiodegradable, compostable, and/or recyclable superabsorbent polymer.

A core forming apparatus is utilized in one embodiment of the presentinvention to create absorbent cores with varying properties, includingcore weight, density, SAP/Fluff ratio, fluff type, SAP type, and thechassis used. These cores mimic compositions run on commercial diaperlines. Cores are formed and tested according to the present invention bypressing a core using a hydraulic press to achieve the desired densityand placing the core in a commercially available diaper chassis fromwhich a commercial core has been removed. Specifically, cores areassembled based on a desired composition by inputting layers of fluffand SAP into the forming apparatus. Vacuum suction pulls the contentsonto a forming drawer with a nonwoven at the base as support. The coreis weighed after the addition of all inputs to assess weight relative tothe target weight, and adjustments are made if the weight is differentfrom the target weight. After the target weight is reached, the core ispressed using a hydraulic press to achieve the target density within+/−0.01 g/cm³. Preferably, dimensions for a core are 40 cm×10 cm;however, cores are operable to be smaller depending on chassis size.After formed, supplemental test methods are utilized to verify the SAPdistribution, SAP content, and SAP: Fluff ratio.

The core is inserted into a diaper chassis from which commercial diapercores have been removed, and a layer of adhesive such as tape isutilized to secure the core into the chassis. Notably, the core is theonly components from the commercial diaper which are replaced. Asassessment of the performance of the core in the commercial diaper onlyinvolves assessment of the core and all preceding layers such as the ADLand top sheet, the replacement of the back sheet does not affect testingperformance. In some embodiments, the cores are tested according to thepresent invention by creating five circles out of each 40 cm×10 cm core.In one embodiment, the circles are punched out from the core. The freeswell (FS), centrifuge retention capacity (CRC), absorbency under load(AUL), acquisition time under load (ATUL), rewet under load (RUL),absorption capacity, and retention capacity of the core are operable tobe tested.

A core forming apparatus is utilized in one embodiment of the presentinvention to create absorbent cores with varying properties, includingcore weight, density, SAP/Fluff ratio, fluff type, SAP type, and thechassis used. These cores mimic compositions run on commercial diaperlines. Cores are formed and tested according to the present invention bypressing a core using a hydraulic press to achieve the desired densityand placing the core in a commercially available diaper chassis fromwhich a commercial core has been removed. Specifically, cores areassembled based on a desired composition by inputting layers of fluffand SAP into the forming apparatus. Vacuum suction pulls the contentsonto a forming drawer with a nonwoven at the base as support. The coreis weighed after the addition of all inputs to assess weight relative tothe target weight, and adjustments are made if the weight is differentfrom the target weight. After the target weight is reached, the core ispressed using a hydraulic press to achieve the target density within+/−0.01 g/cm³. Preferably, dimensions for a core are 40 cm×10 cm;however, cores are operable to be smaller depending on chassis size.After formed, supplemental test methods are utilized to verify the SAPdistribution, SAP content, and SAP: Fluff ratio.

The core is inserted into a diaper chassis from which commercial diapercores have been removed, and a layer of adhesive such as tape isutilized to secure the core into the chassis. Notably, the core is theonly components from the commercial diaper which are replaced. Asassessment of the performance of the core in the commercial diaper onlyinvolves assessment of the core and all preceding layers such as the ADLand top sheet, the replacement of the back sheet does not affect testingperformance. In some embodiments, the cores are tested according to thepresent invention by creating five circles out of each 40 cm×10 cm core.In one embodiment, the circles are punched out from the core. The freeswell (FS), centrifuge retention capacity (CRC), absorbency under load(AUL), acquisition time under load (ATUL), rewet under load (RUL),absorption capacity, and retention capacity of the core are operable tobe tested.

FSC/CRC of Core Punchouts

To test the FSC and CRC of the core, the core circles or “punchouts” areplaced in 4 inch by 4 inch MONETEREY BAY FILL YOUR OWN TEA BAGS “Tea PotSize” tea bags and submerged in a reservoir of 0.9 wt. % NaCl for aduration of 30 minutes. Following swelling, a 10-minute free hangingperiod occurs allowing gravity to remove extra fluid that transferredfrom the reservoir. At the end of the free hanging period, the weight ofeach sample is recorded, and the free swell is calculated on a gram pergram basis. The samples are then placed in a spin dryer and undergo 3minutes of centrifuging at approximately 1300 RPMS. The weight of eachsample is taken following the centrifuging and the centrifuge retentioncapacity is calculated on a gram per gram basis.

AUL of Core Punchouts

To test the AUL of the core, the core punchouts are placed in polymethylmethacrylate (PMMA) acrylic cylinders with 0.0015 inch Steel or NylonPlastic Mesh and a 59 mm OD Polytetrafluoroethylene (PTFE) piston ontop. The rig system is completed by placing the cylinders and pistons onglass filter discs in a stainless steel tray containing 0.9 wt. % NaCland adding a metal weight creating a combined pressure of 0.7 PSI withthe piston for a duration of 60 minutes. At the conclusion of testing,the weight of the punchout in combination with the weight of the rigsystem before and after testing is used to calculate the absorptionunder load on a gram per gram basis.

Acquisition Time/Rewet Under Load (ATUL/RUL)

This testing assesses the time it takes a baby diaper to uptakesubsequent insults and retain the uptake when subjected to a pressuresimulating that applied by a child. Prototype diapers are operable to betested flat or curved, and undergo three doses of 80 mL or 100 mL ofdyed 0.9 wt. % NaCl, depending on the specifications for testing.

A stainless-steel dosing column with a steel mesh bottom havingapproximately 0.0015 inch mesh and three stainless steel dosing ringsprovide a combined pressure of 0.7 PSI for dosing. The specified insultis dosed through a separatory funnel attached to a ring stand while astopwatch, accurate to 1/10^(th) of a second, and a timer set to 10minutes 0 seconds, accurate to 1 second per 1 hour, are simultaneouslystarted. As the insult is absorbed by the diaper, the fluid is visiblyengulfed below the steel mesh of the dosing column. When this occurs,the stopwatch is stopped, and the time is recorded as the acquisitiontime under load (ATUL). At the conclusion of the remaining 10 minutes, astack of qualitative 20-25 μm nominal pore size, 90 mm filter paper isplaced on the insult point, dosed, and a 0.7 PSI weight is placed on thefilter paper for a duration of two minutes. The first dose includes a 80mL dose, the second dose, includes an additional 80 mL dose, and thethird dose includes an additional 80 mL dose, with each dose being partof a separate test. At the conclusion of the two minutes, the filterpaper is weighed and the difference between the original weight of thefilter paper and the weight of the filter paper after two minutes ofbeing subjected to the 0.7 PSI weight is referred to as the rewet underload (RUL). This procedure is repeated two additional times for a totalof three doses and three rewet measurements.

Absorption Capacity and Retention Capacity

This testing determines the total fluid uptake and retention of a babydiaper under approximately 14 inches of water. Prototypes are submergedin 0.9 wt. % NaCl reservoirs of approximately 3500 mL to approximately4000 mL for 30 minutes. At the conclusion of submersion, the protypesenter a 5-minute hanging period over metal grates where gravity removesextra fluid that transferred from the reservoir. At this point, theprototypes are weighed to determine their absorption capacity as gramtotal or on a gram per gram basis. The prototypes are then transferredto a vacuum box and covered with a 1/32″ latex sheet. A pump is turnedon and the latex sheet seals to create a pressure of 14 inches of water.When the desired pressure is achieved, a timer is started for 10minutes. At the conclusion of the 10 minutes, the prototypes are weighedand their retention capacity is determined on gram per gram basis.

The present invention is explained in greater detail in the followingnon-limiting Examples.

EXAMPLES Example 1.1: Extruded Charge-Modified Biopolymer (Example ofCitric Acid Grafted on to Starch at ˜2 mm Scale)

A twin screw conical extruder manufactured by DSM, a parallel twin screwextruder manufactured by Leistritz, and a parallel twin screw extrudermanufactured by Wegner were used to prepare charge-modified starch. Theextruder properties are provided in Table 1. Various extruders listedhere allow for demonstration of scalability from lab scale toproduction-relevant scale. Furthermore, multiple extruders allow fortransposition of process parameters across a range of extruderconfigurations and size.

Additionally, the parallel twin screw extruders manufactured by Lestritzand Wegner supported multiple reactions zones, allowing for increasedcapabilities, including: temperature, screw, and injection profiles.Examples of temperature and injection profiles are found in Examples1.2, 5.1, and 7, below.

TABLE 1 Extruder properties for a range of extruder configurations andsizes Extruder Manufacturer DSM Thermo Fisher Leistritz Wegner ExtruderModel Xplore Process 11 N/A TX-52 Residence Time 0.25-10 mins 0.25-5mins ~3 mins ~3 mins Screw Size (Screw 3 cm 11 mm 18 mm 52 mm Diameter)L/D 5 40 40 27 Die Size 1-2 mm 0.5-11 mm 1 mm & 4.5 2-4 mm mm RotationCo-rotating Co-rotating Co-rotating Co-rotating screws screws screwsscrews Throughput 0.05-0.2 kg/hr 0.1-5 kg/hr 0.5-8 kg/hr 3-30 kg/hr Typeof heating Electric Electric Electric Electric Number of heating 1  8  8 1 zones

In preparing the charge-modified starch, the following parameters werevaried: temperature, screw RPM, and amount of citric acid using eachextruder. Table 2 sets forth the ranges for the temperature, screw RPM,and amount of citric acid tested using each extruder.

TABLE 2 Parameter ranges for charge-modified starch for each extruderRange Range Range Parameter (DSM) (Leistritz) (Wegner) TemperatureRanges (° C.) 90-150 100-120 100-125 RPM Ranges (RPM) 60-200 120-200120-200 Citric Acid Ranges 50-100  50-100  50-100 (wt % relative tostarch)

Starch (Native Corn Starch, Item 18321, Batory Foods, Des Plaines Ill.),citric acid (Item 756707, Univar, Downers Grove, Ill.) as a chargemodifier and plasticizer, and sodium hypophosphate (SHP) (Item S1320,Spectrum Chemical, New Brunswick, N.J.) as a catalyst were combined andhand mixed in powder form. Powder mixtures were loaded into custompowder injectors and input into the extruder feed port. Various amountsof citric acid were added to the mixture as provided in Table 2. Theresulting mixture was added to the extruder as a powder at varyingextrusion conditions as provided in Table 2. The powder mixture wasmelt-blended in the extruder to form a homogeneous blend reaction inwhich the citric acid was grafted onto the starch to form acharge-modified starch, termed starch citrate. In some runs, thischarge-modified starch was utilized as a precursor polymer tosubsequently crosslink to another biopolymer as described in Example 5.Select samples underwent a thermal post treatment following extrusion byway of vacuum oven at 120° C. for 90 mins.

Table 3 provides specific parameters tested on the DSM extruder withresponses described in Table 4 and described below. Each sample wastitrated to determine its charge density, and analyzed via FTIR (atwavelengths of 1720 cm⁻¹) to determine each sample's relative carboxylcontent via methods described below. Additionally, parameters such as DIuptake, and % extractables were measured as qualitative gauges ofmaterial performance.

TABLE 3 Process parameters for preparing charged- modified starch on aDSM extruder Sample # Sample Sample Sample Sample Sample 1.1A 1.1B 1.1C1.1D 1.1E Temperature (° C.) 140 140 100 140 125 RPM 120 120 120 120 120Post Treatment Yes No Yes Yes Yes Citric Acid (wt % 150 150 50 50 75relative to starch) SHP (wt % relative to 20 20 20 20 20 starch)

Fourier Transform Infrared Spectroscopy (FTIR) is a measure of asamples' absorbance/transmittance of wavelengths in the IR spectrum. Theintensity of absorbed IR radiation at a given wavelength can becorrelated to particular covalent bonds. When data is normalized to theC—O stretch peak (˜1000 cm⁻¹), relative peak intensities are used toestimate the amount characteristic groups on the polymer, wheredecreasing transmittance or, inversely, increasing absorbance indicatesan increased degree of reagent grafting.

Alternatively, degree of substitution is preferably quantified utilizingtitration, with FITR data being utilized to verify whether substitutionoccurred. In one embodiment of conductivity titration for calculatingdegree of substitution, a sample is dissolved in deionized H₂O andacidified to pH<2 with HCl to ensure all charge modifier groups arepresent in the acid form (R—CO₂H). This solution is titrated with anNaOH solution. Electrical conductivity measured as titrant is addedfirst decreases, then remains constant, then increases, producing twoendpoints—the first corresponding to the neutralization of excess HCland the second corresponding to the conversion of all charge modifiergroups to the sodium salt form (R—CO₂Na). The degree of substitution(DS) is calculated using Eqn. 1

$\begin{matrix}{{DS} = \frac{A \times n_{{CO}\; 2H}}{m_{ds} - ( {B \times n_{{CO}\; 2H}} )}} & (1)\end{matrix}$where A is the molecular weight of the unsubstituted monomer, B is themolecular weight of the substituent, m_(ds) is the mass of dry sampleobtained by Eqn. 2m _(ds)=Moisture content (in decimal form)×sample weight (grams)  (2)and n_(CO2H) is the moles of anionic moieties obtained by Eqn. 3

$\begin{matrix}{n_{{CO}\; 2H} = {\frac{{V2} - {V1}}{1000} \times C_{NaOH}}} & (3)\end{matrix}$where V₂ and V₁ are the volumes of titrant (in mL) corresponding to thesecond and first endpoints, respectively, and CNaOH is the concentrationof the NaOH solution (in M).

Bonds of interest for biopolymers modified with citric acid (e.g.,starch citrate) include the carboxyl (R—CO₂H) bond at ˜1713 cm⁻¹, wheredecreasing transmittance or, inversely, increasing absorbance indicatesan increased degree of charge density.

Back titration is a measure of charge density in anionic,charge-modified biopolymer samples. The results of this measurementtechnique scale with the FTIR data. As described here in Example 1.1,along with Examples 1.2, 1.3, 2.1, 3.1, 3.2, and 3.3, 0.2-0.3 g ofsample was exposed to 50 mL of 0.05 M NaOH solution for 1 hr. One dropof phenolphthalein (Item 3241N80, Thomas Scientific, Swedesboro, N.J.)was added and mixed into solution to act as a visual indication,approximating neutrality of the solution. A pH probe was used to monitoracid/alkaline nature of the solution during mixing and titration. Thesolution was then titrated with 0.05M HCl at, ˜0.05 mL/second. Thevolume of HCl required to reach pH neutrality was recorded and assumedto be equivalent to the number of moles needed to neutralize excess NaOHin solution. The difference between the recorded moles and initial moleswas then normalized to the original sample weight to yield a mol/g ormeq/g charge density unit.

DI uptake is a measure of a sample's degree of swelling (i.e., itsabsorbency by weight under given conditions). DI uptake was measured byinserting ˜0.25 g sample/cm in 33 mm diameter, of 12-14 kD dialysistubing (Item 684219, Carolina Biological, Burlington, N.C.). The ends oftubing were sealed and labeled, then exposed to 20 mL DI water per gramof sample for 72 hours. DI water was replaced every 2-3 hours over thecourse of a 72 hr period. Samples were then removed from the dialysistubing and weighed. Changes in weight between the initial and final(wet) measurements were normalized to initial mass to grams of DI waterabsorbed per gram of sample (g/g).

Samples were then dried using a forced air oven and/or a freeze dryer.Weight loss between dried sample and initial sample weight (predialysis) was used to calculate extractables as a % of initial sample(inverse of yield). These extractables reflect a measure of the amountof sample that elutes upon initial contact with water. This parameterqualitatively measures the mass fraction of unreacted moieties,plasticizer, and/or degraded polymeric products in a given sample.

TABLE 4 Properties of the charged-modified starch FTIR Titration DIUptake Extractables Sample # (% Trans) (meq/g) (g/g) (%) 1.1A 36 5.9 3.489 1.1B 96 1.9 2.8 87 1.1C 59 2.8 2.7 37 1.1D 48 4.2 3.1 30 1.1E 49 3.85.4 49

As can be seen from Tables 3 and 4, charge-modified starch was producedin the process example of reactive extrusion described here. %Transmittance as measured via FTIR is shown to decrease significantlybelow that of starch (94.5%) while titration values are shown toincrease significantly over that of starch (0 meq/g).

Temperature and citric acid (charge modifying agent) concentration arethe parameters where increasing inputs show increased charge density.Furthermore, inclusion of a thermal post treatment after extrusion alsoshows increasing charge density. Relative similarity and relatively lowvalues of DI uptake parameters across indicate a lack of crosslinking.Extractable values are indicative of excess reagent and generally trendwith charge modifier concentration. FTIR transmittance values achievedranged from approximately 35-98% while charge density values achievedranged from approximately 1 to 6.5 meq/g.

Example 1.2: Extruded Charge-Modified Biopolymer (Example of Citric AcidGrafted on to Starch at 18 mm Scale)

A parallel twin screw extruder with multiple injection and reactionzones manufactured by Leistritz was also used to prepare charge-modifiedstarch citrate. These experiments were performed to determinescalability and behavior of materials through varied reaction zones. Theextruder properties are provided in Table 1 above. FIG. 2 illustratesthe 8-zone extruder with injection ports in this configuration locatedprior to zone 1 and at zone 3.

Raw materials were prepared in a similar manner to extrusion asdescribed above in Example 1.1. However, samples were mixed in 1 kgunits and fed using gravimetric powder feeders manufactured by Brabender(Duisburg, Germany) to account for scale. Studies below utilizedmultiple injection and reaction zones to simulate full-scale extrusionprocesses. Screw profile utilized is described in FIG. 6B (medium shearscrew). Powder samples of each of the following components: starch,citric acid, and SHP were fed into the primary injection zone (prior tozone 1) where the mixture was allowed to react at 120° C. Withoutwishing to be bound to any particular theory, at this temperature thecitric acid dehydrates to yield an anhydride that reacts faster with thefree hydroxyl groups. Temperature profiles for each zone are detailed inTable 5 below. Extrusion and composition parameters for starch citratewere varied as described in Table 6 below. In some runs, extrudedsamples in solid form were post-treated by placing the charge-modifiedstarch in an oven at 120° C. for 90 minutes. Specific examples ofprocess parameters and resulting responses are shown in Tables 7 & 8below, respectively.

TABLE 5 Temperature and injection parameters for charge-modified starchvia parallel twin-screw extruder Zone 1 2 3 4 5 6 7 8 Temperature (° C.)100 105 115 120 120 120 120 115 Injection Starch + Reagents N/A N/A N/AN/A N/A N/A N/A N/A

TABLE 6 Parameter ranges for charge-modified starch via 18 mm, paralleltwin-screw extruder Temperature Ranges (° C.) 100-120 (see Table 5) RPMRanges (RPM) 120-200 Citric Acid Ranges (wt % relative to starch) 50-100

TABLE 7 Process parameters for preparing charged-modified starch via 18mm, parallel twin-screw extruder Sample # Sample Sample Sample Sample1.2A 1.2B 1.2C 1.2D Temperature (° C.) 100-120 100-120 100-120 100-120(multiple (multiple (multiple (multiple zones) zones) zones) zones) RPM100 160 100 170 Post Treatment Yes Yes Yes Yes Citric Acid (wt % rela-100 50 75 75 tive to starch) SHP (wt % relative to 20 20 20 20 starch)

TABLE 8 Properties of the charged-modified starch FTIR Titration DIUptake Extractables Sample # (% Trans) (meq/g) (g/g) (%) 1.2A 35 6.551.7 32 1.2B 53 2.10 1.1 10.5 1.2C 54 2.0 1.8 45 1.2D 43 5.8 1.3 10

As can be seen from Tables 7 and 8, this work demonstrated thefeasibility of producing a charge-modified starch via a reactiveextrusion process. % Transmittance as measured via FTIR is shown todecrease significantly below that of starch (94.5%) while titrationvalues are shown to increase significantly over that of starch (0meq/g). Furthermore, it should be noted that titration and FTIR valueshave a positive correlation. Increased RPM in this method improves thedegree of charge modification as a response to increased shear.

Example 1.3: Extruded Charge-Modified Biopolymer (Example of Citric AcidGrafted on to Starch at 52 mm Scale)

A parallel twin screw extruder manufactured by Wegner was used toprepare charged-modified starch and to further demonstrate scaling. Theextruder properties are provided in Table 1.1 above. Screw profileutilized largely conforms to a purely conveying screw as described inFIG. 6A (low shear screw).

Raw materials for charge-modified starch were prepared in a similarmanner to the extrusion processes described above. However, samples weremixed and injected in ˜2 kg units to account for the larger scale andcontinuous nature of this extruder. Extrusion and composition parametersfor starch citrate were varied as described in Table 9 below. Specificexamples of process parameters and resulting responses are shownrespectively in Tables 10 and 11 below, respectively. In some runs,extruded samples in solid form were post-treated by placing thecharge-modified starch in an oven at 120° C. for 90 minutes.

TABLE 9 Parameter ranges for charge-modified starch via 52 mm, paralleltwin-screw extruder Temperature Ranges (° C.) 100-125 RPM Ranges (RPM)120-200 Citric Acid Ranges (wt % relative to starch)  50-100

TABLE 10 Process parameters for preparing charged-modified starch via 52mm, parallel twin screw extruder Sample # Sample Sample 1.3A 1.3BTemperature (° C.) 110 120 RPM 120 100 Post Treatment Yes Yes CitricAcid (wt % relative to starch) 66 66 SHP (wt % relative to citric acid)20 20

TABLE 11 Properties of the charged-modified starch FTIR Titration DIUptake Extractables Sample # (% Trans) (meq/g) (g/g) (%) 1.3A 65 2.9 N/A64 1.3B 69 2.4 N/A 68

This work demonstrated the feasibility of producing charge-modifiedstarch via a reactive extrusion process. % Transmittance as measured viaFTIR is shown to decrease significantly below that of starch (94.5%)while titration values are shown to increase significantly over that ofstarch (0 meq/g). Examples 1.1E, 1.2C and 1.3 are used to comparesamples at similar processing conditions. It is concluded from thesimilar responses that parameters listed in these examples aretransposable across a significant range of extruder sizes (representingfrom laboratory benchtop to commonly-used industrial sizes).

Example 2.1: Extruded Charge-Modified Biopolymer (Examples of AdditionalAnionic Charge Modifiers Grafted on to Starch)

In addition to citric acid, additional anionic charge modifiers aredemonstrated in the example below. Starch was charged modified usingmaleic anhydride (Item 63200-500G-F, Sigma-Aldrich, MO, St. Louis) acatalyst (NaOH, Reagent ACS, Item 630, GFS Chemicals, Powell Ohio), andplasticizer to form an anionic starch. Table 12 sets forth the rangesfor the temperature, screw RPM, and amount of reagent tested using aProcess 11, 11 mm parallel twin screw extruder as described in Example1.1, above. Screw profile utilized is described in FIG. 6B (medium shearscrew). Specific examples of process parameters and resulting responsesare shown in Tables 13 and 14 below, respectively. In some runs,extruded samples in solid form were post-treated by placing thecharge-modified starch in an oven at 120° C. for 90 minutes.

In addition to charge density (measured via titration), solubility ofeach sample was also studied. Here, purified samples (as described inthe dialysis process above) are used. 0.25 g of sample is mixed into ina beaker with 25 mL of DI water at 60° C. Beaker with mixture is setstirring on hotplate and held at 60° C. for 15 mins. Mixture is thencentrifuged at 250 g (1800 RPM & 7 cm radius) for 20 mins to separatesolid fraction from the liquid fraction, including dissolved solids. Apipette is then used to decant the liquid layer and discarded. Aluminumweigh pans stored in a desiccator and with predetermined weights areused to collect remaining solids. Weigh pans and solids are then driedin a forced air oven for 48 hrs at 40° C. Weigh pans and samples areremoved from the forced air oven and immediately weighed. Sample weightsas a fraction of initial weights are recorded as a % Solubility.

TABLE 12 Parameter ranges of the anionic-modified starch on an 11 mm,parallel twin screw extruder Temperature Ranges (° C.) 85-140 RPM Ranges(RPM) 10-500 Maleic Anhydride Ranges (wt % relative to  5-120 starch)Catalyst (NaOH) Ranges (wt % relative to 2-60 starch) Plasticizer Ranges(wt % relative to starch) Water, Glycerol, & Water/ Glycerol mixes at40%

TABLE 13 Process parameters for preparing anionic-modified starch via 11mm, parallel twin screw extruder Sample # Sample Sample 2.1A 2.1BTemperature (° C.) 110 110 RPM 50 50 Post Treatment No No MaleicAnhydride Ranges 30 60 (wt % relative to starch) Catalyst (NaOH) Ranges12 24 (wt % relative to starch) Plasticizer (wt % relative to starch)Water (40%) Water (40%)

TABLE 14 Properties of the Anionic Modified Starch Sample # FTIR (%Trans) Titration (meq/g) Solubility (%) 2.1A 83 3.26 76 2.1B 73 5.11 84

Data indicated that a charge-modified starch was produced via a reactiveextrusion process. % Transmittance as measured via FTIR is shown todecrease significantly below that of starch (94.5%) while titration andsolubility values are shown to increase significantly over that ofstarch (0 meq/g and 7%, respectively). Ranges of charge density variedfrom 1.3-6.3 meq/g, and solubility varied from 27-86%. The level ofcharge modification of the starch increased with increasing reagentconcentration. Data are further confirmed via increasing solubility withincreasing charge density.

Example 2.2: Extruded Charge-Modified Biopolymer (Examples of CationicCharge Modifiers Grafted on to Starch)

In addition to anionic charges, starch was charge-modified to form acationic starch. The cationic charge-modified starch was prepared byvarying the following parameters: temperature, screw RPM, amount ofcharge modifying reagent (glycidyltrimethylammonium chloride [SigmaAldrich Item 50053-1L]), catalyst (Sodium Hydroxide), and plasticizercontent. Table 15 sets forth the ranges for the studied parameters inthe Leistritz, 11 mm extruder.

TABLE 15 Parameter ranges of the anionic-modified starch on an 11 mm,parallel twin screw extruder Temperature Ranges (° C.) 85-140 RPM Ranges(RPM) 10-500 Glycidyltrimethylammonium  5-150 chloride (wt % relative tostarch) Catalyst (NaOH) Ranges 2-60 (wt % relative to starch)Plasticizer Ranges Water, Glycerol, & Water/ (wt % relative to starch)Glycerol mixes at 40%

Starch powder was mixed with a catalyst (NaOH) in powder form.Plasticizer was then added to the mixture containing the starch andcatalyst and mixed well by hand. The mixture was then input into theextruder.

Table 16 provides specific parameters tested with test responsesdescribed in Table 17. Note, temperature settings were set to apply auniform temperature for all heating zones. Although temperature profileswere utilized in other experiments, they are not detailed here. Screwprofile utilized is described in FIG. 6B (medium shear screw). Eachsample was tested to determine its charge density (degree ofsubstitution) via elemental analysis (measuring nitrogen).

Elemental analysis is used to measure charge density for cationiccharge-modified biopolymer samples, whereas titration is used to measurecharge density for anionic charge-modified biopolymer samples. Elementalanalysis was carried out by means of Perkin Elmer 2400 CHNS Analyzer:The Perkin Elmer 2400 was used to determine total elemental carbon,nitrogen, hydrogen, or sulfur by total combustion. The Degree ofSubstitution (DS) was determined by nitrogen and calculated according toEquation (4) below:

$\begin{matrix}{{{DS} = {{16{2.1}5 \times \frac{\% N}{1401}} - {15{1.6}4 \times \% N}}},} & {{Equation}\mspace{14mu}(4)}\end{matrix}$where DS is the degree of substitution and % N is the measured nitrogencontent. Furthermore, % N is nearly 0% but a non-zero number (e.g.,0.002). It is subtracted from all measurements for precision. Pleasecheck and confirm Equation 4. This seems to yield a negative number.You're subtracting what value from what measurements for precision?

TABLE 16 Process and formulation parameters for preparing cationiccharge-modified starch Sample # Sample Sample Sample Sample 2.2A 2.2B2.2C 2.2D Temperature (° C.) 90 120 90 90 Plasticizer Water Water WaterWater (wt % relative to starch) (40%) (40%) (40%) (40%) RPM 100 120 5050 Post Treatment No No No Yes Glycidyltrimethylammonium chloride 4 8530 30 (wt % relative to starch) NaOH (wt % relative to starch) 1.2 24 1212

TABLE 17 Properties of the cationic charged-modified starch Sample #Degree of Substitution* Solubility (%) 2.2A 0.035 28 2.2B 0.12 68 2.2C0.19 76 2.2D 0.21 13 *Degree of substitution as measured by nitrogencontent

Once again, a charge-modified starch was produced in this reactiveextrusion process. Degree of substitution and solubility values weresignificantly greater than that of starch (0 DS, and 0.4% solubility,respectively) and demonstrate charge modification of a cationic starchvia reactive extrusion. A range of DS values are produced. The DS valuesachieved here are significantly higher than previously reported valuesof DS for cationic starch produced via reactive extrusion.

In example 2.2D, inclusion of post treatment shows increased degree ofsubstitution with simultaneous reduction in solubility indicatingpresence of crosslinking as discussed in later examples.

Example 3.1: Extruded Charge-Modified Biopolymer (Demonstration ofCharge Grafting onto Hemicellulose)

In addition to starch, additional biopolymers were utilized todemonstrate charge modification. Hemicellulose (Xylan fromBeechwood >=90%, Item X4252, Sigma Aldrich, St. Louis Mo.) wascharge-modified with citric acid to form an anionic hemicellulose usingthe DSM extruder described in Example 1.1. In preparing thecharge-modified hemicellulose, the following parameters were varied:temperature, screw RPM, and amount of citric acid. Table 18 sets forththe ranges for the temperature, screw RPM, and amount of citric acidtested using the twin screw conical extruder.

TABLE 18 Parameter ranges for charge-modified hemicellulose via twinscrew conical extruder Temperature Ranges (° C.) 90-150 RPM Ranges (RPM)50-200 Citric Acid Ranges 40-150 (wt % relative to hemicellulose)

Reagents in powder form were hand mixed in 50 g batches, loaded into theextruder using custom powder injectors, and fed into the extruder atfeed rates determined to be relatively and qualitatively consistent.Table 19 provides specific parameters tested with test responsesdescribed in Table 20. The FTIR spectra for the charge-modifiedhemicellulose and for unmodified hemicellulose is provided in FIG. 3.Charge density values are reported according to the titration methoddescribed in Example 1.1. It should be noted that in this example,charge density values of the raw materials are measured and thensubtracted from measured values to show a degree of change in chargedensity above that of the raw biopolymer.

TABLE 19 Process and formulation parameters for preparingcharge-modified hemicellulose Sample # Sample 3.1A Sample 3.1BTemperature (° C.) 140 140 RPM 120 120 Post Treatment No Yes Citric Acid(wt % relative to hemicellulose) 150 150 SHP (wt % relative to citricacid) 20 20

TABLE 20 Properties of the charge-modified hemicellulose Sample # FTIR(% Trans) Titration (meq/g) 3.1A 81.4 1.66 3.1B 53.4 4.68

A charge-modified hemicellulose was produced via reactive extrusion.FTIR analysis shows % Transmission values significantly lower than thatof unmodified hemicellulose (91%) and titration values significantlygreater than that of unmodified hemicellulose (0 meq/g), indicatingcharge modification of the hemicellulose.

Example 3.2: Extruded Charge-Modified Biopolymer (Demonstration ofCharge Grafting onto Pectin)

Pectin (Item 76282, Sigma Aldrich, St. Louis, Mo.) was charge-modifiedto increase the anionic property of pectin by grafting additionalcarboxylic acid groups onto pectin using the DSM extruder described inExample 1.1. Experimental methods followed those in Example 3.1. Table21 sets forth the ranges for the temperature, screw RPM, and amount ofcitric acid tested using the twin screw conical extruder.

TABLE 21 Parameter ranges for charge-modified pectin via twin screwconical extruder Temperature Ranges (° C.) 90-150 RPM Ranges (RPM)50-200 Citric Acid Ranges 40-150 (wt % relative to pectin)

Table 22 provides specific parameters tested with test responsesdescribed in Table 23. If the sample underwent a post treatment, thenthe sample was placed in a vacuum oven at 120° C. for 90 mins. Eachsample was tested to determine its charge density (meq/g), andabsorbance/transmittance via Fourier Transform Infrared Spectroscopy(FTIR) at 1720 cm⁻¹. The FTIR spectra for the charge-modified pectin andfor unmodified pectin is provided in FIG. 4. Charge density values arereported according to the titration method described in Example 1.1. Itshould be noted that in this example, charge density values of the rawmaterials are measured and then subtracted from measured values to showa degree of change in charge density above that of the raw biopolymer.

TABLE 22 Process and formulation parameters for preparingcharge-modified pectin Sample # Sample 3.2A Sample 3.2B Temperature (°C.) 140 140 RPM 120 120 Post Treatment No Yes Citric Acid (wt % relativeto pectin) 150 150 SHP (wt % relative to citric acid) 20 20

TABLE 23 Properties of the charged-modified pectin Sample # FTIR (%Trans) Titration (meq/g) 3.2A 59.1 4.96 3.2B 26.6 5.72

A charge-modified pectin was produced via reactive extrusion. FTIRanalysis shows % Transmission values significantly lower than that ofunmodified pectin (63%) and titration values significantly greater thanthat of unmodified pectin (0 meq/g), indicating charge modification ofthe pectin.

Example 3.3: Extruded Charge-Modified Biopolymer (Demonstration ofCharge Grafting onto Soy Protein)

Soy protein was charge-modified to form an anionic soy protein using theDSM extruder described in Example 1.1. In preparing the charge-modifiedsoy protein, Experimental methods followed those in Example 3.1. Table24 sets forth the ranges for the temperature, screw RPM, and amount ofcitric acid tested using the twin screw conical extruder.

TABLE 24 Parameter ranges for charge-modified soy protein via twin screwconical extruder Temperature Ranges (° C.) 90-150 RPM Ranges (RPM)50-200 Citric Acid Ranges 40-150 (wt % relative to soy protein)

Table 25 provides specific parameters tested with test responsesdescribed in Table 26. If the sample underwent a post treatment, thenthe sample was placed in a vacuum oven at 120° C. for 90 mins. Eachsample was tested to determine its charge density (meq/g), andabsorbance/transmittance via Fourier Transform Infrared Spectroscopy(FTIR) at 1720 cm⁻¹. The FTIR spectra for the charge-modified soyprotein and for unmodified soy protein is provided in FIG. 5. Chargedensity values are reported according to the titration method describedin Example 1.1. It should be noted that in this example, charge densityvalues of the raw materials are measured and then subtracted frommeasured values to show a degree of change in charge density above thatof the raw biopolymer.

TABLE 25 Process and formulation parameters for preparingcharge-modified soy protein Sample # Sample 3.3A Sample 3.3B Temperature(° C.) 140 140 RPM 120 120 Post Treatment No Yes Citric Acid 150 150 (wt% relative to hemicellulose) SHP (wt % relative to soy protein) 20 20

TABLE 26 Properties of the charged-modified soy protein Sample # FTIR (%Trans) Titration (meq/g) 3.3A 68.4 1.66 3.3B 42.8 4.68

A charge-modified soy protein was produced via reactive extrusion. FTIRanalysis shows % Transmission values significantly lower than that ofunmodified soy protein (93%) and titration values significantly greaterthan that of unmodified pectin (0 meq/g), indicating charge modificationof the soy protein. Charge modification was enhanced by thermal posttreatment.

Example 4.1: Extruded Crosslinked Biopolymer (Demonstration of StarchModified with a Range of Crosslinkers)

In addition to charge modifiers, crosslinkers were utilized to form acrosslinked starch using the DSM extruder described in Example 1.1. Inpreparing the crosslinked starch, experimental methods followed those inExample 1.1. The following parameters are varied: temperature, screwRPM, and the amount of crosslinker. In this example, water was used asthe plasticizer at the level of 40 wt % relative to starch. Crosslinkersincluded: Epichlorohydrin (EPI, >=99% (GC), Item 45340, Sigma-Aldrich,St. Louis, Mo.), Poly(ethylene glycol) diglycidyl ether (PEDGE, Avg. MN500, Item 475696, Sigma-Aldrich, St. Louis, Mo.), and Poly(propyleneglycol) diglycidyl ether (PPDGE, Avg. CA. 640, Item 406740,Sigma-Aldrich, MO, St. Louis) with sodium hydroxide as catalyst. Table27 sets forth the ranges for the temperature, screw RPM, and amount ofcrosslinker tested using the twin screw conical extruder. Table 28provides specific parameters tested with test responses described inTable 29.

TABLE 27 Process and formulation ranges for preparing crosslinked starchTemperature (° C.)    80-110 RPM    50-120 Crosslinker Epichlorohydrin,PEDGE, and PPDGE Crosslinker  0.01-0.1 (wt % relative to starch) NaOH(wt % relative to starch) 0.005-0.2

TABLE 28 Process and formulation parameters for preparing crosslinkedstarch Sample # Sample Sample Sample 4.1A 4.1B 4.1C Temperature (° C.)90 90 90 RPM 120 120 120 Post Treatment No No No Crosslinker EPI PEDGEPPDGE Crosslinker (wt % relative to starch) 0.1 0.1 0.1 NaOH (wt %relative to starch) 0.2 0.2 0.2 Plasticizer (40% relative to starch)Water Water Water

TABLE 29 Properties of crosslinked starch Sample # Solubility (%)Swelling (g/g) Sample 4.1A 1.6 0.35 Sample 4.1B 2.53 2.67 Sample 4.1C4.07 3.15

Here, crosslinked biopolymers were produced via a reactive extrusionprocess. Reactive extrusion of starch with crosslinkers show: ascrosslinker chain length (molecular weight) is increased(EPI<PEDGE<PPDGE), swelling values improve beyond that of uncrosslinkedstarch (0.4 g/g) and solubility values approach that of uncrosslinkedstarch (7%).

Example 4.2: Extruded, Crosslinked, Charge-Modified Biopolymer(Demonstration of Cationic Starch Modified with Various Crosslinkers)

Charge-modified starch was utilized to form a crosslinked,charge-modified starch using the DSM extruder described in Example 1.1.In preparing the crosslinked, charge-modified starch, experimentalmethods followed those in Example 4.1. Aquaflocc 330 AW, manufactured byAquasol Corp (Rock Hill, S.C.) was used as the cationic starch in thisexample. Additional commercially-available cationic starches, as well ascationic starches as described in Example 2.2 were also utilized. Thefollowing parameters are varied: temperature, screw RPM, amount ofcrosslinker, and plasticizer. Crosslinkers included: Epichlorohydrin,Poly(ethylene glycol) diglycidyl ether, and Poly(propylene glycol)diglycidyl ether with sodium hydroxide as catalyst. Table 30 sets forththe ranges for the temperature, screw RPM, and amount of crosslinkertested using the twin screw conical extruder. Table 31 provides specificparameters tested with test responses described in Table 32.

TABLE 30 Process and formulation ranges for preparing crosslinked,cationic starch Temperature (° C.) 80-160 RPM 10-300 Crosslinker (wt %relative to starch) 0.0001-10    NaOH (wt % relative to starch)0.001-20    Plasticizer (%) Water, Glycerol (20-50%)

TABLE 31 Process and formulation parameters for preparing crosslinked,cationic starch Sample # Sample Sample Sample 4.2A 4.2B 4.2C Temperature(° C.) 90 90 90 RPM 120 120 120 Post Treatment No No No Crosslinker EPIPEDGE PPDGE Crosslinker (wt % relative to starch) 0.1 0.1 0.1 NaOH (wt %relative to starch) 0.2 0.2 0.2 Plasticizer (% relative to starch) WaterWater Water (40%) (40%) (40%)

TABLE 32 Properties of crosslinked cationic starch Sample # Solubility(%) Swelling (g/g) Sample 4.2A 12.6 1.9 Sample 4.2B 39.9 11.2 Sample4.2C 40.3 14.7

Here, crosslinked, charge-modified biopolymers were created via reactiveextrusion. Solubility results show values significantly lower than thatof the raw material (84%). Here, decreasing solubility indicatesincreased a degree of crosslinking. Swelling results may be higher orlower than that of the raw material (4.4 g/g) depending on degree ofcrosslinking.

Example 5.1: Extruded Crosslinked, Charge-Modified Biopolymer(Demonstration of Crosslinking Multiple Biopolymers Using 2-Step, inLine Method)

To demonstrate crosslinking two charge-modified biopolymers,crosslinked, charge-modified starch citrate chitosan was prepared usinga 2-step inline process using the Leistritz, 18 mm extruder as describedin Example 1.1. Grafting citric acid onto starch provides an anioniccharge, which changes the degree of charge as can be measured using backtitration (meq/g). Acetic acid protonates chitosan upon mixing, therebyproviding a cationic charge on the chitosan. The charge-modifiedchitosan is assumed to be partially (i.e., 50% or more) or fully (100%)protonated due to its solubility in water.

Furthermore, the extruder having multiple zones as shown in FIG. 2,allows for implementation of temperature and injection profiles.Extrusion and composition parameters for preparing crosslinked,charge-modified starch citrate chitosan were varied as described inTable 33. Here, powder samples of starch, citric acid, and SHP were fedinto the initial injection zone (Step 1), while chitosan (TradingResources, Cocoa Beach, Fla.), acetic acid (Sigma Aldrich, Item #A6283,St. Louis, Mo.), and plasticizers were simultaneously added in atinjection zone 3 (Step 2) as shown in Table 34 below. Reactions zones1-2 were used for charge modification, while reaction zones 3-8 wereused for crosslinking the charge-modified starch to charge-modifiedchitosan. Temperature profiles for each zone are provided in Table 34below. Screw profile utilized largely conforms to the medium shear screwas described in FIG. 6B (medium shear screw). After the graft reactionof citric acid onto starch, the temperature was decreased to 100° C. toallow for the injection of protonated chitosan inside the extruder inzone 3 before raising the temperature to 105° C. and 110° C. in zones 4and 5, respectively, to initiate the crosslinking reaction between thestarch carboxylate and the free amine groups on the backbone ofchitosan. In some runs, extruded samples in solid form were post-treatedby placing the charge-modified, crosslinked polymer in an oven at 120°C. for 90 minutes. The simultaneous injection of two mixturesdemonstrated below is defined as a 2-step, inline reaction.

TABLE 33 Parameter ranges for crosslinked starch citrate chitosan viaparallel twin screw extruder Temperature Ranges (° C.) 100-120 (seeTable 34) RPM Ranges (RPM) 140-170 Chitosan Ranges (wt % relative tostarch) 100 Acetic Acid Ranges (wt % relative to chitosan)  33 StarchCitrate Ranges (wt % relative to chitosan) 100 Plasticizer Types CitricAcid Plasticizer Ranges (wt % relative to chitosan)  90-140

TABLE 34 Example of temperature and injection profile forcharge-modified starch crosslinked to another biopolymer via paralleltwin-screw extruder Zone 1 2 3 4 5 6 7 8 Temperature 120 120 100 105 110110 110 105 (° C.) Injection Starch + N/A N/A Chitosan + N/A N/A N/A N/AN/A Reagents Reagents

Specific examples of process parameters and resulting responses areshown in Tables 35 and 36 below, respectively. The methods fordetermining the measured responses (e.g., solubility, DI uptake, andextractables) are described in Example 1. For FTIR analysis, bonds ofinterest for charged-modified starch, crosslinked to chitosan systeminclude the Amide-Carbonyl (R—CO—CNH—R) stretch at ˜1650 cm⁻¹.

TABLE 35 Process parameters for preparing crosslinked, charge-modifiedstarch citrate chitosan Sample # Sample 5.1A Sample 5.1B Sample 5.1CTemperature (° C.) 100-120 100-120 100-120 (multiple (multiple (multiplezones) zones) zones) RPM 140 140 170 Post Treatment Yes No Yes ReactionType 2-step inline 2-step inline 2-step inline Plasticizer Type CitricAcid Citric Acid Citric Acid Plasticizer (wt % relative to 75 75 75chitosan) Starch Citrate (wt % relative 100 100 100 to chitosan) AceticAcid (wt % relative to 33 33 33 chitosan)

TABLE 36 Properties of the crosslinked, charge- modified starch citratechitosan Solubility FTIR DI Uptake Extractables Sample # (%) (% Trans)(g/g) (%) 5.1A 4.1 67.5 2.6 19 5.1B 2.4 65.4 9.5 69 5.1C 4.1 68.2 1.9 19

As described in Example 2, charge-modified polymers without crosslinkingshow increasing solubility with increasing charge density (>5% and up to100%). Due to the presence of charge-modified starch and charge-modifiedchitosan, solubility values <5% indicate presence of crosslinking. FTIRanalysis confirms presence of the amide-carbonyl stretch where amodified and unmodified chitosan shows transmission values of 26% andmodified and unmodified starch shows values of 5%. % Transmission valuesabove 26% indicate presence of charge-modified starch crosslinked tocharge-modified chitosan, confirming the ability to form acharge-modified biopolymer crosslinked to another biopolymer in a2-step, in-line method.

Example 5.2: Extruded Crosslinked, Charge-Modified Biopolymer(Demonstration of Crosslinking Multiple Biopolymers Using 2-Step, 2-PassMethod)

To demonstrate a method where charged-modified biopolymers are producedand subsequently crosslinked to another biopolymer, charged-modifiedstarches as prepared in Example 1.1 were crosslinked with chitosan bymixing powdered starch citrate (i.e., the citric acid-modified starch)with acetic acid, chitosan, and plasticizer so that the mixture was inpowdered form. To obtain the powdered charge-modified starch, thecharge-modified starch was ground using a blender to sugar/starchconsistency where there were no visible chunks/inconsistencies in thepowder mixtures. At least one plasticizer selected from: glycerol [Item#0854, Amresco, Solon, Ohio], citric acid, and polyethylene glycol[molecular weights of 400, 800, 20,000, Sigma Aldrich, St. Louis, Mo.]was added to the mixture including starch citrate, acetic acid,chitosan, and plasticizer to induce melt blending during the extrusionprocess. The resulting powder mixture was added to the extruderdescribed in Example 1.1 in a method resembling the process forpreparing charge-modified starch as described in Example 1.1. Extrusionparameters and compositions were modified according to Table 37 below.

TABLE 37 Parameter ranges for crosslinked, charge-modified starchcitrate chitosan via twin screw conical extruder Temperature Ranges (°C.) 90-130 RPM Ranges (RPM) 60-200 Chitosan Ranges (wt % relative tostarch) 50-150 Acetic Acid Ranges (wt % relative to chitosan)  5-100Starch Citrate Ranges (wt % relative to 150-250  chitosan) PlasticizerTypes Glycerol, Citric Acid, Water Plasticizer Ranges (wt % relative tochitosan) 120-275 

Completion of the reaction in two steps is defined here as a “2-step,2-pass” reaction. Examples of process parameters for crosslinked,charge-modified starch citrate chitosan and measured responses are shownin Tables 38 and 39, respectively below. The charge-modified starch usedto prepare the crosslinked, charge-modified starch citrate chitosan hadpreviously been prepared as described in Example 1 according toparameters described in sample 1.1A.

Each sample was analyzed via FTIR to characterize chemical identity,determine its deionized water (DI) uptake, and to measure extractables(inverse of yield) following the methods described in Example 1.

TABLE 38 Process parameters for preparing crosslinked, charge-modifiedstarch citrate chitosan Sample # Sample 5.2A Sample 5.2B Extruder DSMDSM Temperature (° C.) 100 110 RPM 120 120 Post Treatment No No ReactionType 2-step, 2-pass 2-step, 2-pass Plasticizer Type Citric Acid CitricAcid Plasticizer (wt % relative to chitosan) 175 175 Starch Citrate (wt% relative to 100 250 chitosan) Acetic Acid (wt % relative to chitosan) 33  33

TABLE 39 Properties of the crosslinked starch citrate chitosan Sample #FTIR (% Trans) DI Uptake (g/g) Extractables (%) 5.2A 59.4 2.7 73 5.2B62.6 1.5 61

As described in Example 5.1, a citric acid modified starch crosslinkedto chitosan shows the amide-carbonyl (R—CO—CNH—R) stretch at ˜1650 cm⁻¹when subjected to FTIR analysis. FTIR analysis confirms presence of theamide-carbonyl stretch where a modified and unmodified chitosan showstransmission values of 26% and modified and unmodified starch showsvalues of 5%. Here, % Transmission values of 59 and 62% (>26%) indicatepresence of charge-modified starch crosslinked to charge-modifiedchitosan and confirming the ability to form a charge-modified biopolymercrosslinked to another biopolymer in a 2-step, 2-pass method.

Example 5.3: Extruded Crosslinked, Charge-Modified Biopolymer(Demonstration of Crosslinking Multiple Biopolymers Using All-In-OneMethod)

To demonstrate simultaneous charge modification and crosslinking viareactive extrusion, all raw materials (i.e., starch, citric acid, SHP,chitosan, acetic acid, and plasticizer as described in Examples 5.1 and5.2) were injected simultaneously in powder form to induce chargemodification and crosslinking reactions in one injection throughmultiple extruders (defined here as an “all-in-one” reaction). Here, themixture of all raw materials was added to the extruder described inExample 1.1 and 1.3 in a method resembling the process for preparingcharge-modified starch as described in Example 1.1 and 1.3. Extrusionparameters and compositions were modified according to Table 40 below.Examples of process parameters for preparing crosslinked,charge-modified starch citrate chitosan are shown in Table 41 below withmeasured responses provided in Table 42. The methods for determining themeasured responses are provided in Examples 1 and 2.

TABLE 40 Parameter ranges for crosslinked, charge-modified starchcitrate chitosan via twin screw conical extruder and 52 mm, paralleltwin screw extruder Extruder DSM Wegner TX-52 Temperature Ranges (° C.)90-130 105-130 RPM Ranges (RPM) 60-200 120-250 Chitosan Ranges (wt %relative to 50-150 50-75 starch) Acetic Acid Ranges (wt % relative 5-100 N/A to chitosan) Starch Ranges (wt % relative to 150-250  100chitosan) Plasticizer Types Glycerol, Citric Citric Acid, Acid, PolyEthylene Water Glycol, Water Plasticizer Ranges (wt % relative 120-275 100-130 to chitosan)

TABLE 41 Process parameters for preparing crosslinked, charge-modifiedstarch citrate chitosan Sample # Sample Sample Sample Sample 5.3A 5.3B5.3C 5.3D Extruder DSM DSM Wegner Wegner TX-52 TX-52 Temperature (° C.)100 133 120 110 RPM 120 120 120 200 Post Treatment No No No No ReactionType All-in- All-in- All-in- All-in- one one one one Plasticizer TypeCitric Glycerol Citric Citric Acid Acid Acid Plasticizer (wt % relative175 175 100 100 to chitosan) Starch (wt % relative to 150 100 150 150chitosan) Citric Acid (wt % relative 66 66 N/A N/A to starch) SHP (wt %relative to 20 20  20  20 starch) Acetic Acid (wt % relative 33 33 N/AN/A to chitosan)

TABLE 42 Properties of the crosslinked, charge- modified starch citratechitosan Sample # FTIR (% Trans) DI Uptake (g/g) Extractables (%) 5.3A58.8 4.3 58 5.3B 66.9 4.9 54 5.3C 67.2 N/A 67 5.3D 65.3 N/A 65

As described in Example 5.1 and 5.2, a citric acid modified starchcrosslinked to chitosan shows the Amide-Carbonyl (R—CO—CNH—R) stretch at˜1650 cm⁻¹ when subjected to FTIR analysis. The presence of carbonylgroups indicates citric acid charge modification on starch, and thepresence of the Amide-carbonyl group indicates crosslinking. FTIRanalysis confirms presence of the Amide-carbonyl stretch where amodified and unmodified chitosan shows transmission values of 26% andmodified and unmodified starch shows values of 5%. Here, % Transmissionvalues of >26% indicate simultaneous charge modification andcrosslinking of charge-modified starch crosslinked to chitosan to form acharge-modified biopolymer crosslinked to another biopolymer in anall-in-one method.

Example 6: Example of Modified Biopolymer for IEX Application(Demonstration of Salt/Heavy Metal Uptake)

To demonstrate ion removal capabilities of a charge-modified,crosslinked biopolymer, citric acid-modified starch crosslinked tochitosan were prepared according to Examples 5.1, 5.2, and 5.3. Sampleswere tested for their salt uptake capacity measured by conductivity andash content post exposure to a saline solution.

Ash content testing is a measure of residual inorganic material in asample upon exposure to high temperatures. 0.3 g of samples was exposedto a 10% saline (NaCl) solution for 5 minutes, then squeezed by hand toremove absorbed liquids. Samples were then transferred to clean, dry,glass vials whose weights were previously recorded. Samples were thenexposed to high temperatures in a muffle furnace (Vulcan, Model 3-550),for 4 hours at 575° C. following TAPPI Standard: T211 om-02—“Ash inwood, pulp, paper and paperboard, combustion at 525° C.” (2002), whichis incorporated herein by reference in its entirety. To determine theash content, the vial weight was subtracted from the final recordedweight of vial and ash. Final ash weight was assumed to be residualcaptured salts where the final ash weight is divided by the initialsample weight to normalize data to a g NaCl/g sample (g/g) format.

Conductivity is a measure of ionic mobility in a given solution.Reductions in conductivity are attributed to captured ions, changes insystem energy (i.e., temperature, pressure, etc.), and/or potential ofdissolved ions (i.e., pH changes in presence of acids/bases). Samples(0.3 g) were exposed to 25 mL of 10% NaCl solution where initialconductivity (Metler-Toledo conductivity instrument [model #51302530])was measured to be 142 mS/cm with a standard deviation of 3.7. Finalconductivity measurements were assumed to be attributed to ion captureand was therefore used to calculate a percent difference in conductivity(captured salt). The uptake of salt was correlated to the resultingdecrease in conductivity by the following formula:Salt Uptake=(volume in mL*salinity*% Δ)/sample weight,where % Δ is the % change in conductivity. The % change in conductivityis attributed to a reduction in mass of NaCl in solution and isnormalized to samples weight. The resulting measurement parameter yieldssalt uptake as g NaCl/g sample.

TABLE 43 Salt removal properties of a charge-modified and crosslinkedbiopolymer system Salt Uptake - Conductivity Salt Uptake - Ash ContentSample # (g/g) (g/g) 5.1A 0.24 0.98 5.1B 0.22 1.1  5.1C 0.16 0.69 5.2A0.13 N/A 5.2B 0.13 N/A 5.3A N/A 0.1  5.3B 0.25 0.74 5.3C 0.2  N/A 5.4D0.24 N/A

Here, salt uptake results of a crosslinked biopolymer (crosslinkedcationic starch as prepared via the method found in Example 4.2) asmeasured by conductivity show values of 0 g/g. The presence ofamphoteric charge (including both cationic and anionic chargesimultaneously) is expected to improve the polymer's interaction withfree ions in solution and is shown in Table 43. Data demonstrated theability of charge-modified and crosslinked biopolymers to remove ionsfrom solution at a greater rate than a crosslinked biopolymer. Saltuptake is further demonstrated through ash content measurements as shownin Table 43 above.

Example 7: Example of Modified Biopolymer for SAP Application(Demonstration of Charge-Modified Starch (Cationic) Crosslinked to FormSuperabsorbent

A superabsorbent polymer was prepared using a commercially availablecharged cationic starch (AquaFlocc 330AW) and a catalyst on the P11extruder described in Example 1.1. The extruder having multiple zonessimilar to that shown in FIG. 2, allows for implementation oftemperature and injection profiles. Screw profile utilized is describedin. FIG. 6B (medium shear screw). Extrusion and composition parametersfor preparing a material for superabsorbent material were varied asdescribed in Table 44. In preparing the superabsorbent polymer, powdercationic starch (Aquafloc 330AW) and sodium hydroxide were fed into theinitial injection zone via volumetric powder feeder (Volumetric MiniTwinFeeder for Process 11, Typ 567-7660, Thermo Electron/Thermo FisherScientific, Germany), while plasticizer (glycerol) was simultaneouslyadded in at injection zone 2 via liquid injector and peristaltic pump(Masterflex P/S Peristaltic Pump, Model No 1300-3600-0004, Thermo FisherScientific, USA) with corresponding peristaltic pump head (MasterflexP/S Easy Load II, Model No 955-0000, Thermo Fisher Scientific, USA). Insome runs, extruded samples in solid form were post-treated by placingthe modified cationic polymer in an oven at 120° C. for 90 minutes. Thesimultaneous injection of two mixtures demonstrated below is defined asa 2-step, inline reaction.

In preparing the absorbent polymers, the following parameters werevaried: temperature, screw RPM, plasticizer, plasticizer concentration,and amount of catalyst. Table 44 sets forth the ranges for thetemperature, screw RPM, and amount of catalyst tested using the 11 mm,parallel twin screw extruder.

Samples were tested as absorbents using the EDANA/INDA method WSP240.2.R3: Free swell capacity in saline by gravimetric determination inorder to measure the fluid uptake of samples (2012), which isincorporated herein by reference in its entirety. For the gravimetricmethod, 0.2 g of sample was sealed in a 2″×2″ teabag. The teabag/samplepacket was submerged in a solution for 1 hr, then hanged to dry for 10mins. Solutions were prepared according to an industrially relevantapplication (0.9% NaCl). Weight measurements were recorded pre- and-post submerging and normalized for a teabag control sample undergoingthe same conditions. The calculation was as follows:

${FSC} = \frac{W_{w} - W_{b} - W_{i}}{W_{i}}$where W_(w) is the wet weight of the teabag/sample, W_(b) is the wetweight of the teabag alone, and W_(i) is the initial weight of theteabag/sample.

TABLE 44 Parameter ranges absorbent polymers via twin screw conicalextruder Temperature Ranges (° C.) 80-160 RPM Ranges (RPM) 50-200Plasticizer Water, Glycerol, PEG Plasticizer (wt % relative 20-60% tocat. starch) NaOH (wt % relative  0-30% to cat. starch)

Table 45 provides specific parameters tested with specific temperatureprofiles shown in Table 46 and test responses described in Table 47.Each sample was tested to determine its swelling capacity according tothe method described above, and solubility according to the method inexample 2. Temp Profile 7 in Table 45 is equal to the temperatureslisted in Table 46

TABLE 45 Process and formulation parameters for absorbent polymersSample # Sample 7A Sample 7B Temperature (° C.) Temp Profile TempProfile 7 7 RPM 150 80 Post Treatment Yes Yes Plasticizer (wt % relativeGlycerol Glycerol to cat. starch) (25%) (25%) NaOH (wt % relative to7.5%  7.5%  cat. starch)

TABLE 46 Temperature and injection profiles for samples 7A and 7B:charge-modified starch via 11 mm, parallel twin-screw extruder SampleZone # 1 2 3 4 5 6 7 8 Die Temp Profile 7 Unheated 70  75 80 95 110 100100 100 (° C.) Injection Cat. Starch + Glycerol N/A N/A N/A N/A N/A N/AN/A NaOH 7A Feed Rate 50   5.9 N/A N/A N/A N/A N/A N/A N/A (RPM) 7B FeedRate 25   2.4 N/A N/A N/A N/A N/A N/A N/A (RPM)

TABLE 47 Properties of the absorbent polymers Sample Free SwellSolubility # Capacity (g/g) (g/g) 7A 31.6 4.5 7B 28.8 2.0

As shown by results in Table 47, reactive extrusion is used to make abiopolymer material that is useful for absorbing liquids in industriallyrelevant applications.

Example 8: Example of Modified Biopolymer for Biosorbent Application

Additionally, samples as described in Example 7 were tested asabsorbents for other fluids using a modified the EDANA/INDA method WSP240.2.R3: free swell capacity in saline by gravimetric determination inorder to measure the fluid uptake of samples. Here, alternativesolutions are used as shown in Table 48, in place of the specified 0.9%NaCl (saline). Instant Ocean Sea Salt was used as a sea water stimulant.Canola oil, conventional motor oil, and synthetic motor oil were used asoil references. Gasoline and diesel fuel were used as fuel references,and whole bovine blood was used as a blood reference. The resultsdemonstrated an improved performance for crosslinked, charge-modifiedbiopolymers of the present invention relative to conventionalsuperabsorbent materials: Sodium Polyacrylate (NaPoly, Item 432784,Sigma-Aldrich, St. Louis, Mo.) in Table 48 below.

TABLE 48 Biosorbent properties of a crosslinked, charge-modifiedbiopolymer of the present invention (“Modified Biopolymer”) relative tocommercially available superabsorbent polymers (NaPoly) Uptake SolutionSample (g/g) Instant Ocean Modified Biopolymer 29 (Sea Water) Na Poly 19Canola Oil Modified Biopolymer 18 Na Poly 2.2 Motor Oil ModifiedBiopolymer 5.3 (Conventional) Na Poly 1.7 Motor Oil Modified Biopolymer9.2 (Synthetic) Na Poly 2.3 Gasoline Modified Biopolymer 3.9 Na Poly 0.8Diesel Modified Biopolymer 4.7 Na Poly 3.4 Blood Modified Biopolymer16.6 Na Poly 1.48

As shown by results in Table 48, reactive extrusion is used to make abiopolymer material that is useful for absorbing liquids in a range ofindustrially relevant applications.

Example 9: Example of Modified Biopolymer Showing ComparativeHomogeneity (Homogeneity Analysis)

A JEOL JSM-6010LA scanning electron microscopy (SEM) with a solid stateEDS detector was used to characterize and compare samples. Samples wereadhered to a mount using double sided carbon tape and analyzed at 20 kV.Micrographs were collected along with corresponding EDS scans of thetarget area.

Indications of homogeneity were derived from the comparison ofcommercially available cationic starch to an extruded cationic starch ofthe present invention (Example 2.2C). AquaFlocc 330AW manufactured byAquasol Corp (Rock Hill, S.C.) represented the commercially availablestarch. It is believed that the commercially available cationic starchis modified in a dry process, which maintains starch in granular formand allows only for surface modification of the starch. In contrast, theextrusion process is believed to completely destroy the granularstructure of the biopolymer (e.g., starch).

As can be seen in FIGS. 7A and 7B, which are SEM images of commerciallyavailable starch, the commercially available starch retains the starch'scharacteristic granular structure. In contrast, as can be seen in FIGS.7D and 7E, which are SEM images of extruded cationic starch preparedaccording to methods of the present invention, starches extrudedaccording to embodiments of the present invention exhibit completedestruction of the granular structure and morphology arises only fromtopology in sample preparation. This can be seen by comparing FIGS. 7Aand 7B with FIGS. 7D and 7E.

Furthermore, when exposed to water and dried, the commercially availablestarches showed the presence of insoluble materials. These insolublematerials indicate uncharged or lowly charged regions, which are aproduct of inhomogeneous processing. These results were confirmed viaEnergy-Dispersive X-ray Spectroscopy (EDS of EDXS), which was used tomap the elemental composition of the SEM image for the commerciallyavailable starch (FIG. 7C) and the extruded cationic starch preparedaccording to methods of the present invention (FIG. 7F). As can be seenin FIG. 7C, a clear/defined dark region is present where the discreteparticles are imaged. This indicates that these particles are differentin composition (lacking chlorine) compared to the surrounding region. Incontrast, as can be seen in FIG. 7F, EDS scans of the extruded starchshow a gradual change in contrast towards the bottom right of the image.This change correlates to a sloping region on the SEM image towards thebottom right. However, the top left of the image in FIG. 7F also shows asloping region in the SEM image, with little change in the EDS map.Thus, it can be concluded that any contrast here is from a shadowingeffect, rather than a compositional effect and the sample is thereforehomogeneous.

Example 10: Interior Crosslinked Modified Starch Prepared with ModifiedCarboxymethyl Starch Produced Via Reactive Extrusion

A modified starch was produced via reactive extrusion. The extrudate wassolubilized in water and adjusted with a crosslinking agent. Theisolated modified starch was then dried to remove excess water.Subsequently, the isolated modified starch was thermally treated.Crosslinking parameters are displayed in Table 49 while crosslinkingoutputs are displayed in Table 50.

Notably, the isolated crosslinked modified starch particles arebiocompostable according to ASTM D5338 guidelines. No alcohol was usedas a reagent during the charge modification step of the extrusionprocess.

This formulation is one formulation which does not include surfacecrosslinking or any meaningful amount of surface crosslinking, and isreferred to as a formulation for modified biopolymer 1 throughout thepresent specification. The material was milled and screened to ensurethe particle size met distribution guidelines (between about 150 micronsand about 850 microns).

TABLE 49 Interior Crosslinking Parameters Parameters CrosslinkerCrosslinker 1 Crosslinker Concentration 0.3 wt. % Relative to ModifiedStarch

Example 11: Surface Crosslinked & Interior Crosslinked Modified StarchPrepared Using Preferred Crosslinkers

The interior crosslinked modified starch was prepared in the mannerdescribed in Example 10. In separate procedures, solutions containingcrosslinkers were added to the surface of interior crosslinked modifiedstarch. Once the material was coated, it was thermally treated. Thedried material was screened to ensure the particle size meetsdistribution guidelines.

The resulting surface-crosslinked modified starch properties aredetailed in Table 50. According to ASTM D6866-18 Biobased contenttesting, the surface crosslinked charge modified starch particlesproduced have at least 75% biobased carbon content as a percent of totalorganic carbon. Each of the surface crosslinked modified starchesnotably has a CRC of at least about 14 g/g, at least about 15 g/g,between about 14 g/g and about 19 g/g, or between about 15 g/g and about19 g/g. Each of the surface crosslinked modified starches notably has anAUL at 0.7 psi of at least about 8 g/g, at least about 9 g/g, betweenabout 8 g/g and about 12 g/g, between about 8 g/g and about 11 g/g,between about 9 g/g and about 12 g/g, or between about 9 g/g and about11 g/g.

Notably, the modified biopolymers which utilize these crosslinkers arebiocompostable, i.e. the modified biopolymers degrade by at least 90%relative to an analytical grade cellulose control in less than 180 daysaccording to the modified ASTM D5338 described above. The modifiedbiopolymers also have at least 80% biobased carbon content as a percentof total organic carbon according to the ASTM D6866 Carbon 14 Test. Themodified biopolymers are biodegradable.

Advantageously, the modified biopolymers are particularly suitable forhygiene applications as they exhibit no cytotoxicity and are not dermalirritants. Cytotoxicity of the modified biopolymers was tested accordingto ISO 10993-5, using the fully swollen hydrogel form in MinimumEssential Medium (MEM) solution in direct contact with cultures of mousefibroblast L929 cells for 48 hours. The viability of the exposed cellswas assessed directly surrounding the test article, with no biologicalreactivity of the modified biopolymers with exposed cells. The modifiedbiopolymers are considered to have no cytotoxic effect (Grade 0).Cytotoxicity of the modified biopolymers was tested according to ISO10993-5, 2009, Biological Evaluation of Medical Devices—Part 5: Testsfor In Vitro Cytotoxicity, using extractions obtained of the swollenhydrogel form exposed to cultures of mouse fibroblast L929 cells for 48hours. The viability of the cells after exposure was assessed usingstandard MTT assay. The extracts of the modified biopolymers were foundto have no biological reactivity with exposed cells, and the modifiedbiopolymers are considered to have no cytotoxic effect (Grade 0). Dermalirritation of the modified biopolymers was tested according to OECD 439,Organization for Economic Cooperation and Development (OECD). Guidelinesfor the Testing of Chemicals, “In Vitro Skin Irritation: ReconstructedHuman Epidermis Test Method”, adopted July 2013, using extractionsobtained from the swollen hydrogel form exposed to in vitro skin tissuemodel EpiDerm™. The viability of the cells after exposure was assessedusing standard MTT assay. The viability of the cells exposed to themodified biopolymers exceeded 100% and the modified biopolymers areconsidered non-irritating. This testing was conducted by ToxikonCorporation, Bedford Mass., in compliance with current U.S. Food andDrug Administration 21 CFR, Part 58 Good Laboratory Practices forNonclinical Laboratory Studies. As chemicals such as epichlorohydrin areknown carcinogens in animals, and are reasonably anticipated to becarcinogens in humans, these chemicals are preferably not used ascrosslinkers in hygiene applications due to concerns about cytotoxicityand/or dermal irritation.

Additionally, the primary irritation potential of the modifiedbiopolymers was determined using a 48 hour patch test. The modifiedbiopolymers were added in powder form to saline solution in the ratio of1.0 g of modified biopolymer per 34 g of saline solution or 3.0 g ofmodified biopolymer per 100 g of saline solution. The solution was mixedwell and allowed to rest for at least 10 minutes, but not more than 24hours, to form a gel-like test material for testing. Approximately 0.2 gof the test material was applied to a 0.75 inch by 0.75 inch absorbentpad portion of an adhesive dressing, which was secured to an appropriatetreatment site to form an occlusive patch. The test material remained incontact with the skin for a total of 2 days, and the site was evaluatedfor gross changes. Absence of any visible skin change was assigned azero value. There was no visible skin reaction in any of 100 subjects ofboth male and female genders whose ages ranged from 18 to 79. There wereno adverse events, no amendments, and no deviations. Accordingly, thetest material indicated no potential for dermal irritation.

These formulations utilize both internal crosslinking and surfacecrosslinking, and are referred to as formulations for modifiedbiopolymer 2 throughout the present specification.

TABLE 50 FSC CRC AUL (g/g) (g/g) (g/g) at 0.7 Sample (Saline) (Saline)psi (Saline) Sample #1 40 32 5.5 Sample #2 32 19 9.6 Sample #3 31 17 11Sample #4 30 15 11 Sample #5 31 17 10.3 Sample #6 34 19 11 Sample #7 3016 11 Sample #8 33 18 10 Sample #9 31 17 12

Example 12: Surface Crosslinked & Interior Crosslinked Modified StarchPrepared Using Alternative Crosslinkers

The interior crosslinked modified starch was prepared in the mannerdescribed in Example 10. In separate procedures, solutions of thecrosslinkers listed in Table 51 below were added to the surface ofinterior crosslinked modified starch in order to obtain the coatings inthe percentages listed in Table 51 below. Once the material was coated,it was thermally treated. The dried material was screened to ensure theparticle size meets distribution guidelines.

The resulting surface-crosslinked modified starch properties aredetailed in Table 51. These formulations utilize both internalcrosslinking and surface crosslinking, and are referred to asformulations for modified biopolymer 2 throughout the presentspecification. Advantageously, these modified biopolymers have at least75% biobased carbon content as a percent of total organic carbon.

TABLE 51 AUL at FSC CRC 0.7 psi 1st Surface 2nd Surface (g/g) (g/g)(g/g) Crosslinker Crosslinker (Saline) (Saline) (Saline) Firstcrosslinker Second crosslinker 34 18 10 First crosslinker Secondcrosslinker 32 15 10 First crosslinker Second crosslinker 26 12 12 Firstcrosslinker NONE 32 18 6 First crosslinker NONE 35 20 7 Firstcrosslinker NONE 38 26 7 First crosslinker NONE 36 24 6 Firstcrosslinker Second crosslinker 32 17 10 First crosslinker Secondcrosslinker 30 14 10 First crosslinker NONE 33 17 8 First crosslinkerNONE 35 19 8 First crosslinker Second crosslinker 33 20 7 Firstcrosslinker Second crosslinker 34 19 6 First crosslinker Secondcrosslinker 34 20 7 First crosslinker Second crosslinker 33 17 10 Firstcrosslinker Second crosslinker 35 16 11 First crosslinker Secondcrosslinker 32 18 10 First crosslinker Second crosslinker 28 16 10 Firstcrosslinker Second crosslinker 32 16 10 First crosslinker Secondcrosslinker 30 15 11 First crosslinker NONE 35 19 7 First crosslinkerNONE 32 17 6 First crosslinker NONE 34 17 5 First crosslinker NONE 41 355 First crosslinker Second crosslinker 31 16 13 First crosslinker Secondcrosslinker 31 17 13 First crosslinker Second crosslinker 31 16 11 Firstcrosslinker Second crosslinker 30 15 13 First crosslinker Secondcrosslinker 28 14 15 First crosslinker Second crosslinker 29 14 12 Firstcrosslinker NONE 38 24 7 First crosslinker NONE 35 22 6 Firstcrosslinker NONE 35 21 7 First crosslinker Second crosslinker 34 18 8First crosslinker Second crosslinker 36 19 8 First crosslinker NONE 3724 6 First crosslinker NONE 35 16 11 First crosslinker NONE 29 14 14First crosslinker NONE 30 15 13 First crosslinker NONE 36 20 9 Firstcrosslinker NONE 29 13 13 First crosslinker Second crosslinker 31 17 13First crosslinker Second crosslinker N/A 15 12 First crosslinker Secondcrosslinker 30 15 12 First crosslinker Second crosslinker N/A 15 12First crosslinker NONE 33 19 11 First crosslinker NONE 34 18 9 Firstcrosslinker NONE 30 16 7 First crosslinker NONE 29 16 8 Firstcrosslinker NONE 31 16 7 First crosslinker NONE 31 15 9

Example 13: Surface Crosslinked & Interior Crosslinked Modified StarchPrepared Using Other Alternative Crosslinkers

The interior crosslinked modified starch was prepared in the mannerdescribed in Example 10. In separate procedures, crosslinkers were addedto the surface of interior crosslinked modified starch. Once thematerial was coated, it was thermally treated. The dried material wasscreened to ensure the particle size meets distribution guidelines.

The resulting surface-crosslinked modified starch properties aredetailed in Table 52. Properties of the surface-crosslinked modifiedstarch were tested in saline and defibrinated sheep's blood according toa modified FSC ran with defibrinated sheep's blood and a modified CRCran with defibrinated sheep's blood.

These formulations utilize both internal crosslinking and surfacecrosslinking, and are referred to as formulations for modifiedbiopolymer 2 throughout the present specification. Advantageously, thesemodified biopolymers have at least 75% biobased carbon content as apercent of total organic carbon.

TABLE 52 Avg Avg FSC CRC (g/g) (g/g) Avg Avg (Defi- (Defi- Bulk SurfaceFSC CRC brinated brinated cross- cross- (g/g) (g/g) Sheep's Sheep'slinker linker (Saline) (Saline) Blood) Blood) First Second 32 19 23 16cross- cross- linker linker First Second 36 30 13 12 cross- cross-linker linker First Second 35 18 18 14 cross- cross- linker linker FirstSecond 40 30 6 5 cross- cross- linker linker

Example 14: Surface Crosslinked & Interior Crosslinked Modified StarchPrepared Using Alternate Crosslinkers

The interior crosslinked modified starch was prepared in the mannerdescribed in Example 10. In separate procedures, a first and secondcrosslinker were added to the surface of the interior crosslinkedmodified starch. Once the material was coated, it was thermally treated.The dried material was screened to ensure the particle size meetsdistribution guidelines.

The resulting surface-crosslinked modified starch properties aredetailed in Table 53.

These formulations utilize both internal crosslinking and surfacecrosslinking, and are referred to as formulations for modifiedbiopolymer 2 throughout the present specification.

TABLE 53 AUL at 1st Surface 2nd Surface FSC CRC 0.7 psi CrosslinkerCrosslinker (g/g) (g/g) (g/g) relative wt. % relative wt. % (Saline)(Saline) (Saline) First crosslinker Second 34 20 7 crosslinker Firstcrosslinker Second 32 16 9 crosslinker First crosslinker Second 32 16 13crosslinker First crosslinker Second 37 21 7 crosslinker Firstcrosslinker Second 40 26 6 crosslinker First crosslinker Second 31 15 3crosslinker First crosslinker Second 25 12 1 crosslinker Firstcrosslinker NONE 34 17 6 First crosslinker NONE 33 16 4 Firstcrosslinker NONE 34 20 6 First crosslinker NONE 33 16 7 Crosslinker ACrosslinker B 32 18 14

A range of pre-thermal treatment mixing times were tested. After mixing,the now coated interior crosslinked modified starch was thermallytreated with a range of curing times. The dried material was screened toensure the particle size meets distribution guidelines.

The resulting surface-crosslinked modified starch properties aredetailed in Table 54. These formulations utilize both internalcrosslinking and surface crosslinking, and are referred to asformulations for modified biopolymer 2 throughout the presentspecification.

TABLE 54 1st 2nd AUL at Surface Surface Mixing Cure FSC CRC 0.7 psiCross- Cross- Time Time (g/g) (g/g) (g/g) linker linker (Minutes)(Minutes) (Saline) (Saline) (Saline) Cross- Cross- Mixing Cure 36 23.68.5 linker A linker B Time A Time A Cross- Cross- Mixing Cure 36 23.58.6 linker A linker B Time B Time A Cross- Cross- Mixing Cure 37 24.08.7 linker A linker B Time C Time A Cross- Cross- Mixing Cure 35 23.19.0 linker A linker B Time D Time A Cross- Cross- Mixing Cure 36 23.38.0 linker A linker B Time E Time A Cross- Cross- Mixing Cure 37 24.07.9 linker A linker B Time F Time A Cross- Cross- Mixing Cure 36 22.910.4 linker A linker B Time G Time A Cross- Cross- Mixing Cure 34 22.511.4 linker A linker B Time H Time A Cross- Cross- Mixing Cure 35 23 9.7linker A linker B Time I Time A Cross- Cross- Mixing Cure 35 23.9 9.5linker A linker B Time J Time A Cross- Cross- Mixing Cure 35 21.8 11.5linker A linker B Time I Time B Cross- Cross- Mixing Cure 32 18.1 14.4linker A linker B Time I Time C

Example 15: Surface Crosslinked & Interior Crosslinked Modified PotatoStarch Prepared Using Crosslinkers

Potato starch having an amylose content of approximately 80% and anamylopectin content of approximate 20% was extruded. The extrudate wassolubilized in water and amounts of a first crosslinker and a secondcrosslinker were added in varying amounts. The SAP was then separatedfrom solution and cured.

The resulting performance of each of the modified biopolymers ispresented in Table 55 below. These formulations utilize internalcrosslinking only, and are referred to as formulations for modifiedbiopolymer 1 throughout the present specification.

TABLE 55 AUL at FSC CRC 0.7 psi (g/g) (g/g) (g/g) Crosslinker Mix(Saline) (Saline) (Saline) Crosslinker Mix A 25 16 6 Crosslinker Mix B24 15 7 Crosslinker Mix C 21 13 10 Crosslinker Mix D 30 20 6 CrosslinkerMix E 30 25 5 Crosslinker Mix F 33 25 6 Crosslinker Mix G 28 20 5Crosslinker Mix H 27 19 7 Crosslinker Mix I 27 17 8 Crosslinker Mix J 2717 7

Example 16: Surface Crosslinked & Interior Crosslinked Charge ModifiedStarch Blended with Commercially Available Non-Biobased SAP

A range of blends between the surface crosslinked and interiorcrosslinked charge modified starch synthesized using Crosslinker A orCrosslinker B, and a commercially available SAP, were prepared andabsorbance properties measured. Additionally, a range of blends betweenthe charge modified starch synthesized just using Crosslinker C and acommercially available SAP, were tested. The results of these tests aredetailed below in Table 56.

TABLE 56 Percent Percent non-Com- SAP A mercial Blends with Blends withw/w or biobased CRC SAP A SAP B SAP B SAP Delta SAP Blend FSC CRC FSCCRC N/A N/A N/A (g/g) (g/g) (g/g) (g/g) 100% SAP A or 30.9 18.2 36.323.3 100%  0% 28% SAP B w/w 100% Commer- 57.7 33.9 57.7 33.9  0% 100%cially Available Non-Biobased SAP w/w 60% SAP A or 41.6 24.5 44.8 27.6 60%  40% 13% SAP SAP B w/w 50% SAP A or 44.3 26.0 47.0 28.6  50%  50%10% SAP B w/w 45% SAP A or 45.7 26.8 48.1 29.1  45%  55%  9% SAP B w/w40% SAP A or 47.0 27.6 49.1 29.7  40%  60%  7% SAP B w/w 35% SAP A or48.3 28.4 50.2 30.2  35%  65%  6% SAP B w/w 25% SAP A or 51.0 30.0 52.431.3  25%  75%  4% SAP B w/w 20% SAP A or 52.4 30.8 53.4 31.8  20%  80% 3% SAP B w/w

A further range of blends of SAP A and SAP C blended with a commercialnon-biobased SAP were tested. SAP A has a FSC of 30.9 g/g, a CRC of 18.4g/g and an AUL of 8.4 g/g, SAP C has a FSC of 22.2 g/g, a CRC of 15.6g/g and an AUL of 7.6 g/g, and the commercial non-biobased SAP has a FSCof 57.7 g/g, a CRC of 33.9 g/g and an AUL of 22.2 g/g. The results ofthe tests of these blends are detailed below in Table 57.

TABLE 57 Percent SAP A Percent SAP A SAP C or SAP C w/w Comm SAP CRC FSCCRC FSC CRC Delta SAP Blend (g/g) (g/g) (g/g) (g/g) N/A N/A N/A 100% SAPA or SAP 30.9 18.2 22.2 15.6 100% 0% −14% C w/w 100% commercial 57.733.9 57.7 33.9 0% 100% N/A non-biobased SAP 60% SAP A or SAP 41.6 24.536.4 22.9 60% 40% −6% B w/w 50% SAP A or SAP 44.3 26.0 40.0 24.7 50% 50%−5% B w/w 45% SAP A or SAP 45.7 26.8 41.7 25.7 45% 55% −4% B w/w 40% SAPA or SAP 47.0 27.6 43.5 26.6 40% 60% −4% B w/w 35% SAP A or SAP 48.328.4 45.3 27.5 35% 65% −3% B w/w 30% SAP A or SAP 49.7 29.2 47.1 28.430% 70% −3% B w/w 25% SAP A or SAP 51.0 30.0 48.8 29.3 25% 75% −2% B w/w20% SAP A or SAP 52.4 30.8 50.6 30.2 20% 80% −2% B w/w

Example 17: Surface Crosslinked & Interior Crosslinked Charge ModifiedStarch Prepared Using Crosslinker A and Crosslinker B

The surface crosslinked and interior crosslinked charge modified starchsynthesized from Crosslinker A and Crosslinker B, was also taken andmixed with a commercially available non-biobased SAP in ratios of 40:60,45:55, and 50:50 by weight. An additional surface crosslinked andinterior crosslinked charge modified starch superabsorbent was alsomade.

The resulting performance of each SAP blend is presented in Table 58below.

TABLE 58 FSC of CRC of Pure SA, Pure SA Superabsorbent Used (g/g) (g/g)35/65 SAP A w/w/ commercial 48.3 28.4 non-biobased SAP 40/60 SAP B w/w/commercial 49.1 29.7 non-biobased SAP 45/55 SAP B w/w/ commercial 48.129.1 non-biobased SAP 50/50 SAP B w/w/ commercial 47.0 28.6 non-biobasedSAP

Example 18: First Surface Crosslinked & Interior Crosslinked ChargeModified Starch and Surface Crosslinked & Second Interior CrosslinkedCharge Modified Starch

In an alternate synthesis path, SAP C was synthesized and mixed withcommercial non-biobased SAP in ratios of 35:65, 30:70, and 25:75 byweight. An additional superabsorbent blend was made using a 35:65 ratioof SAP A to commercial non-biobased SAP.

The resulting performance of each blend type is presented in Table 59below.

TABLE 59 FSC of CRC of Pure Pure Superabsorbent Used SA, g/g SA, g/g35/65 SAP A w/w/ commercial 48.3 28.4 non-biobased SAP 35/65 SAP C w/w/commercial 45.3 27.5 non-biobased SAP 30/70 SAP C w/w/ commercial 47.128.4 non-biobased SAP 25/75 SAP C w/w/ commercial 48.9 29.3 non-biobasedSAP

Example 19: Free Swell Capacity of Biobased and Commercial SAPs

A surface crosslinked and interior crosslinked charge modified starchwas turned into a powder to measure the FSC. Several commerciallyavailable SAPs were also turned into powder. The free swell capacity ofthe surface crosslinked and interior crosslinked charge modified starchwas tested against the commercial SAPs using 0.9% saline solution.

Table 60 displays the free swell capacity of the interior crosslinkedcharge modified starch against the commercially available SAPs.

TABLE 60 Free Swell Capacity SAP Liquid (g/g) Polyacrylic acid A Saline66 Polyacrylamide A 59 Commercial non- 56 biobased SAP Polyacrylic acidD 51 SAP A 32 SAP A formed via alternative process 21

SAP B was taken and mixed with a wood pulp fluff, in a 60:40 ratio ofSAP to wood pulp fluff. This SAP has a FSC of 36.3 g/g, a CRC of 23.3g/g, and an AUL of 8.1 g/g at 0.7 psi in 0.9% NaCl.

The SAP and fluff mixture was placed in a commercial diaper chassis. Asecond superabsorbent core was made using SAP A. This SAP has a FSC of30.9 g/g, a CRC of 18.4 g/g and an AUL of 8.4 g/g. This superabsorbentcore was produced in the same way as the previous core, using a 60:40ratio of SAP to wood pulp fluff, with the SAP and fluff mixture beingplaced in a commercial diaper chassis. A third superabsorbent core wasmade by mixing polyacrylate-based SAP with wood pulp fluff in a 60:40ratio of SAP to wood pulp fluff and incorporating the mixture into acommercial diaper chassis. The polyacrylate-based SAP has a FSC of 57.7g/g, a CRC of 33.9 g/g and an AUL of 22.2 g/g.

The resulting performance of each core is displayed in Table 61 below.All data displayed is the average of measurements taken from fourcommercial chassis.

TABLE 61 Absorption Retention FSC of CRC of Saline Saline Result/Result/ Core SAP Pure Pure Absorbed Retained Core Core Weight Amount SASA SAP (g) (g) Wt (g/g) Wt (g/g) (g) (g) (g/g) (g/g) SAP A 638 381 30.117.9 21.2 12.6 29.0 18.6 SAP F 694 415 32.6 19.5 21.3 12.6 36.3 23.3Commercial 818 582 39.0 27.7 21.0 12.6 53.4 35.6 Polyacrylate SAP

The three different core types were also tested for liquid absorptiontime and rewet capacity. The results of these tests, includingacquisition time under load (ATUL) and Rewet Under Load (RUL), aredetailed below in Table 62. All data displayed is the average ofmeasurements taken from four to eight commercial chassis.

TABLE 62 3rd First Second Third First Second Third Core SAP Rewet SalineATUL ATUL ATUL RUL RUL RUL Wt. Amt per Core Retained SAP (sec) (sec)(sec) (g) (g) (g) (g) (g) Weight (g) SAP A 96 135 178 1.59 14.8 31.521.2 12.6 1.49 381 SAP F 88 120 149 0.18 8.98 20.4 21.3 12.6 0.96 415Commercial 74 101 129 0.05 0.45 6.72 21.0 12.6 0.32 582 Polyacrylate SAP

SAP F was also taken and mixed with a commercial non-biobased SAP inratios of 40:60, 45:55, and 50:50 by weight. Each mixture of surfacecrosslinked and interior crosslinked charge modified starch synthesizedfrom SAP F and a commercial non-biobased SAP was then added to wood pulpfluff in a 60:40 ratio of SAP to fluff. The wood pulp fluff andsuperabsorbent mixture was then placed in a commercial chassis andsoaked for 30 minutes. SAP A was also added to wood pulp fluff in a60:40 ratio of SAP to fluff. The wood pulp fluff and superabsorbentmixture was then placed in a commercial chassis and soaked for 30minutes.

The resulting performance of each core type is displayed in Table 63below. All data displayed is the average of measurements taken from 4commercial chassis.

TABLE 63 Ret Absorption Retention FSC CRC as Result Result of of SalineSaline % (g/g) (g/g) Core Pure Pure Superabsorbent Absorbed Retained ofCore Core Weight SA, SA Used (g) (g) Cap Wt. Wt. (g) (g/g) (g/g) 35/65SAP A 710 415 58% 34.0 19.8 20.9 48.3 28.4 w/w/commercial non-biobasedSAP 40/60 SAP F 725 486 67% 34.5 23.2 21.0 49.1 29.7 w/w/commercialnon-biobased SAP 45/55 SAP F 711 459 65% 34.0 22.0 20.9 48.1 29.1w/w/commercial non-biobased SAP 50/50 SAP F 686 439 64% 32.7 20.9 21.047.0 28.6 w/w/commercial non-biobased SAP Fluff only, no 247 117 N/A N/AN/A 8.4 N/A N/A superabsorbent

The four different core types also had their liquid absorption time andrewet capacity tested. The results of these tests are detailed below inTable 64. All data displayed is the average of measurements taken from 4commercial chassis.

TABLE 64 First Second Third First Second Third Total Core AcquisitionAcquisition Acquisition Rewet Rewet Rewet Rewet Weight SAP Ratio Time(sec) Time (sec) Time (sec) (g) (g) (g) (g) (g) 35/65 SAP A 99 133 1680.06 6.75 18.5 25.3 20.9 w/w/commercial non-biobased SAP 40/60 SAP F 100134 166 0.10 6.89 18.7 25.6 21.0 w/w/commercial non-biobased SAP 45/55SAP F 96 135 165 0.06 4.61 20.1 24.8 20.9 w/w/commercial non-biobasedSAP 50/50 SAP F 88 119 153 0.05 4.67 19.2 23.9 21.0 w/w/commercialnon-biobased SAP

The absorption capacity, retention capacity, average primary, secondary,and tertiary ATUL, average primary, secondary, and tertiary RUL, andcore weight was also measured for another set of chassis with blends ofbiobased SAP and commercial SAP. The biobased SAP has a FSC of 29.0 g/g,a CRC of 18.6 g/g, an AUL of 8.6 g/g, and a permeability of 2.5 g/g in acore made according to the present invention. The commercial SAP has aFSC of 53.4 g/g, a CRC of 35.6 g/g, an AUL of 19.7 g/g, and apermeability of 4.7 g/g in a core made according to the presentinvention. The SAP: fluff ratio of each core was 60:40.

TABLE 65 Abs. Ret. Avg Avg Avg Avg Avg Avg Core Cap. Cap. ATUL- ATUL-ATUL- RUL- RUL- RUL- Wt. SAP (g) (g) P (s) S (s) T (s) P (g) S (g) T (g)(g) Commercial 788 560 73 97 112 0.06 0.15 2.02 20.2 non-biobased SAP20/80 biobased 732 515 78 101 120 0.09 0.27 4.30 20.2 SAP/ commercialnon-biobased SAP w/w 35/65 biobased 695 480 77 101 123 0.07 0.67 5.2220.2 SAP/ commercial non-biobased SAP w/w 50/50 biobased 670 448 78 105125 0.07 2.05 12.53 20.2 SAP/ commercial non-biobased SAP w/w

Other blends were tested in different chassis, and the results wererecorded below.

TABLE 66 Saline Saline Absorption Retention Core Absorbed RetainedResult Result Weight Diaper Type SAP (g) (g) (g/g) (g/g) g CommercialCommercial 667 446 20.0 13.4 20.3 Diaper 1 Diaper SAP ExperimentalCommercial 865 637 21.3 15.7 20.2 Core in Diaper SAP Commercial Diaper 1Experimental 80/20 Blend 811 561 19.5 13.5 20.2 Core in CommercialCommercial Diaper SAP/ Diaper 1 Biobased SAP Experimental 63/35 Blend775 526 18.6 12.6 20.2 Core in Commercial Commercial Diaper SAP/ Diaper1 Biobased SAP Experimental 50/50 Blend 718 486 17.4 11.8 20.2 Core inCommercial Commercial Diaper SAP/ Diaper 1 Biobased SAP ExperimentalBiobased 543 330 17.0 10.3  20.2* Core in SAP Commercial Diaper 1

TABLE 67 Core ATUL- ATUL- ATUL- RUL- RUL- RUL- Wt. Diaper Type SAP P (s)S (s) T (s) P (g) S (g) T (g) (g) Commercial Commercial 69 85 96 0.060.27 5.61 20.3 Diaper 1 Diaper SAP Experimental Commercial 77 101 1250.05 0.05 0.57 20.2 Core in Diaper SAP Commercial Diaper 1 Experimental80/20 Blend 75 104 125 0.05 0.10 3.63 20.2 Core in Commercial CommercialDiaper SAP/ Diaper 1 Biobased SAP Experimental 63/35 Blend 81 103 1360.06 0.11 3.07 20.2 Core in Commercial Commercial Diaper SAP/ Diaper 1Biobased SAP Experimental 50/50 Blend 85 116 145 0.05 1.47 8.58 20.2Core in Commercial Commercial Diaper SAP/ Diaper 1 Biobased SAPExperimental Biobased 63 107 345 0.08 8.17 30.2  20.2* Core in SAPCommercial Diaper 1

Example 20: Blends of SAP A & SAP F in Diaper Cores

SAP F was synthesized in an alternate synthesis path. SAP F was mixedwith a commercial non-biobased SAP in ratios of 35:65, 30:70, and 25:75by weight before being taken and mixed with a wood pulp fluff, in a60:40 ratio of SAP to fluff. Each of these mixtures was placed in acommercial chassis and soaked for 30 minutes. An additionalsuperabsorbent core was made using a 35:65 blend of the surfacecrosslinked and interior crosslinked charge modified starch synthesizedusing SAP F and the commercial non-biobased SAP. This superabsorbentmixture was then mixed with wood pulp fluff in a 60:40 ratio of SAP tofluff. This core was placed in a commercial chassis and soaked for 30minutes.

The resulting performance of each core type is displayed in Table 68below. All data displayed is the average of measurements taken from 4commercial chassis.

TABLE 68 Retention FSC CRC Saline Absorption Result of of Super- SalineSaline as % Result (g/g) Core Pure Pure absorbent Absorbed Retained of(g/g) Core Weight SA, SA, Used (g) (g) Cap Core Wt. Wt g g/g g/g 35/65SAP 729 490 67% 34.5 23.2 21.1 48.3 28.4 A/commercial non-biobased SAPw/w 35/65 SAP 676 463 69% 32.0 21.9 21.1 45.3 27.5 F/commercialnon-biobased SAP w/w 30/70 SAP 680 476 70% 32.4 22.7 21.0 47.1 28.4F/commercial non-biobased SAP w/w 25/75 SAP 694 486 70% 32.9 23.0 21.148.9 29.3 F/commercial non-biobased SAP w/w Fluff Only 242 130 N/A N/AN/A 8.3 N/A N/A No Super- absorbent

The four different core types also had their acquisition time and rewetcapacity tested. The results of these tests are detailed below in Table69.

TABLE 69 First Second Third First Second Third Core SAP/ AcquisitionAcquisition Acquisition Rewet Rewet Rewet Weight Fluff SAP Ratio Time(s) Time (s) Time (s) (g) (g) (g) (g) ratio 35/65 SAP 105 131 165 0.117.78 19.0 21.1 60/40 A/commercial non-biobased SAP w/w 35/65 SAP 101 124153 0.06 8.51 21.1 21.1 60/40 F/commercial non-biobased SAP w/w 30/70SAP 100 124 150 0.14 7.36 20.0 21.0 60/40 F/commercial non-biobased SAPw/w 25/75 SAP 102 123 158 0.06 10.27 23.4 21.1 60/40 F/commercialnon-biobased SAP w/w

Example 21: Properties of Interior Crosslinked Charge Modified CornStarch Prepared Using SAP A

To better establish a baseline for the properties of SAP A, a secondround of tests were run. Prototype diaper cores were constructed asdescribed above, with the diaper cores weighing approximately 21 gramsand including a 60/40 ratio of SAP to wood pulp fluff with a density of0.18+/−0.2 g/cm³. These cores were formed and housed inside a commercialchassis. The SAP for each diaper core was composed by blending acommercially available polyacrylate SAP with the interior crosslinkedcharge modified starch in varying ratios from 100% interior crosslinkedcharge modified starch, to 50% interior crosslinked charge modifiedstarch, to 0% interior crosslinked charge modified starch. Theabsorption capacity and retention capacity of these housed cores wastested. Additionally, the pure SAP blends, not mixed with wood pulpfluff or housed in a commercial chassis were tested to determine theirfree swell capacity, centrifuge retention capacity, and absorption underload according to the methods described above.

The results of these tests are detailed below in Table 70.

TABLE 70 Ret. Percent Abs. Result/ FSC of CRC of of SAP Abs. Ret. Ret.as Result/ Core Pure Pure A in Capacity Capacity % of Core Wt Weight SASA CRC as % Blend (g) (g) Capacity (g/g) (g/g) g/g g/g of FSC 100% 585344 59% 28.0 16.5 31.8 18.9 59  75% 627 386 62% 30.3 18.6 37.7 24.2 64 50% 679 452 67% 32.7 21.7 44.3 26.1 59  25% 722 500 69% 34.9 24.1 51.030.0 59  0% 785 553 70% 37.9 26.7 56.4 34.0 60

Comparing the absorption capacity and retention capacity values to thefree swell and centrifuge retention capacity values as they relate tothe percent of interior crosslinked charge modified starch used in theSAP blend, a unique property of the interior crosslinked charge modifiedstarch becomes apparent. Looking at the values for the pure (100%interior crosslinked charge modified starch) interior crosslinked chargemodified starch, subtracting the absorption result per core weight (g/g)from the free swell capacity, a difference of 3.8 g/g is obtained.Performing the same operation of subtracting the absorption result percore weight (g/g) from the free swell capacity for the pure commercial(0% interior crosslinked charge modified starch) polyacrylate, adifference of 18.5 g/g is obtained. Comparing these two values, there isa notably smaller gap between absorption and free swell capacity for theinterior crosslinked charge modified starch than for the commercialpolyacrylate. The same type of result is obtained when looking atretention capacity and centrifuge retention capacity, where the pureinterior crosslinked charge modified starch has a difference of 2.4 g/g,and the pure commercial polyacrylate has a difference of 7.3 g/g.

FIG. 16 illustrates a chart showing the Capacity/Core Wt and FSC vsPercent SAP A w/w in Blends with commercial non-biobased SAP. Notably,the slope of capacity is a shallower slope than a slope of the pure SAPwithout integration into a core. This is an unexpected result, as thegraph indicates that SAP A provides improved performance characteristicsbeyond what would be expected by merely integrating the SAP with thecore.

Example 22: Properties of Cores with Different SAP: Fluff Ratios

Prototypes were constructed as described above. Diaper cores weighingapproximately 27 grams with a density of 0.18+/−0.2 g/cm³ wereconstructed with SAP: wood pulp fluff ratios of 50:50, 60:40, and 70:30.These cores were then housed inside a commercial chassis. BiodegradableSAPs synthesized according to the present application were utilized asthe SAP in each diaper core. Absorption, retention, ATUL, and RUL of theresulting cores were determined.

The results of these tests are detailed below in Table 71.

TABLE 71 Abs. Ret. Result/ Result/ SAP: Core Core RUL- RUL- RUL- FluffWt Weight ATUL- ATUL- ATUL- P S T Ratio (g/g) (g/g) P (s) S (s) T (s)(g) (g) (g) 50/50 26.0 15.5 84 121 146 2.62 13.43 23.33 60/40 26.5 16.288 123 150 1.42 13.73 23.65 70/30 27.6 16.7 86 118 155 1.32 12.97 22.85

Example 23: Performance of Surface Crosslinked and Interior CrosslinkedCharge Modified Starch Prepared Using SAP F Blend

To determine the effectiveness of using SAP F as the sole diaper SAP,new cores housed in commercial chassis were formed in the same processas detailed in Example 22. Additionally a housed core was constructed ofthe commercial polyacrylate used in Example 22. These housed cores weretested against commercial diapers to compare their performance in theabsorption and retention of saline solution.

The results of these tests are detailed below in Table 72.

TABLE 72 Abs. Ret. Saline Saline Result Result SAP Core SAP/ SAP TypeAbs. Ret. Core Core Amt Wt. Fluff Diaper Type and Target (g) (g) Weight(g/g) Weight (g/g) (g) (g) ratio Experimental 100% SAP F; 817 539 27.918.4 20.5 29.3 70/30 Cores 1.4X Amount of SAP Experimental 100% Comm 809548 38.7 26.2 12.5 20.9 60/40 Cores SAP Experimental 100% SAP F; 734 45429.4 18.1 16.3 25.0 65/35 Cores 1.2X Amount of SAP Commercial Average671 469 31.6 22.1 11.7 21.2 N/A Diapers Experimental 100% SAP F 631 37330.5 18.0 12.4 20.7 60/40 Cores Cloth None 374 207 7.2 4.0 None 52 N/ADiapers Commercial Comm. SAP 647 419 21.9 14.2 3.2 29 N/A Diaper 2Commercial Comm. 767 546 38.2 23.7 N/A 20 N/A Diaper 7 Diaper SAPCommercial Comm. 682 484 25.6 15.8 N/A 27 N/A Diaper 3 Diaper SAPCommercial Comm. SAP 720 483 40.7 27.3 10 18 N/A Diaper 4 CommercialComm. 681 463 30.9 18.1 N/A 22 N/A Diaper 5 Diaper SAP Commercial Comm.667 446 31.8 13.4 N/A 21 N/A Diaper 1 Diaper SAP Commercial Comm. 507390 25.4 19.5 None 20 N/A Diaper 6 Diaper SAP

Example 24: Performance of SAP F in Variety of Cores

The saline absorbed, saline retained, ATUL, and RUL were tested in avariety of cores for SAP F. The results are outlined in Tables 73 & 74below.

TABLE 73 Diaper Saline Saline Absorption Retention Core Chassis SAPAbsorbed (g) Retained (g) Result (g/g) Result (g/g) Weight (g)Commercial Comm. 767 546 22.1 17.2 20.1 Diaper 7 Diaper SAP CommercialSAP F 799 567 23.1 16.4 21.5 Diaper Chassis 7 Commercial Diaper 667 44620.0 13.4 20.3 Diaper 1 Company SAP Commercial SAP F 746 531 23.4 16.719.3 Diaper 1 Commercial Diaper 703 496 20.2 14.3 17.7 Diaper 4 CompanySAP Commercial SAP F 731 524 20.0 14.4 19.3 Diaper 4

TABLE 74 Core Diaper ADL ATUL- ATUL- ATUL- RUL- RUL- RUL- Weight TypeSAP gsm P (s) S (s) T (s) P (g) S (g) T (g) (g) Commercial SAP F 77 4966 133 0.11 0.63 8.0 17.7 Diaper 4 Commercial Diaper 77 64 85 101 0.050.06 1.6 19.4 Diaper 4 Company SAP Commercial SAP F 51 55 66 117 0.041.7 14.7 20.3 Diaper 1 Commercial Diaper 51 58 76 103 0.05 0.03 1.7 19.3Diaper 1 Company SAP Commercial SAP F 82 56 86 141 0.05 0.07 6.4 20.1Diaper 7 Commercial SAP F 82 51 59 83 0.08 0.09 2.8 21.5 Diaper Chassis7

The above-mentioned examples are provided to serve the purpose ofclarifying the aspects of the invention, and it will be apparent to oneskilled in the art that they do not serve to limit the scope of theinvention. By nature, this invention is highly adjustable, customizableand adaptable. The above-mentioned examples are just some of the manyconfigurations that the mentioned components can take on. Allmodifications and improvements have been deleted herein for the sake ofconciseness and readability but are properly within the scope of thepresent invention.

What is claimed is:
 1. An absorbent sanitary article, comprising: afluid-permeable top layer; a fluid-resistant back layer; and anabsorbent core; wherein the absorbent core includes an absorbent fiberand a superabsorbent polymer (SAP); wherein the SAP includes a chargemodified starch-based biopolymer; wherein a biobased carbon content ofthe charge modified starch-based biopolymer is at least approximately80%; wherein the charge modified starch-based biopolymer has aCentrifuge Retention Capacity (CRC) of at least 17 g/g, an AbsorbencyUnder Load (AUL) of at least 7 g/g at 0.7 psi, and a Free Swell Capacity(FSC) of at least 30 g/g in a saline solution; and wherein the chargemodified starch-based biopolymer exhibits no cytotoxicity and is not adermal irritant.
 2. The article of claim 1, wherein the primary rewetunder load of the absorbent core is less than about 3.0 grams in saline.3. The article of claim 2, wherein the secondary rewet under load of theabsorbent core is less than about 14 grams in saline.
 4. The article ofclaim 3, wherein the tertiary rewet under load of the absorbent core isless than about 24 grams in saline.
 5. The article of claim 1, whereinat least 85% of the particle sizes of the charge modified starch-basedbiopolymer are between 100 and 650 microns.
 6. The article of claim 1,wherein the charge modified starch-based biopolymer is crosslinked usingat least two crosslinkers.
 7. The article of claim 1, wherein the chargemodified starch-based biopolymer is not a graft polymer.
 8. The articleof claim 1, wherein the CRC of the charge modified starch-basedbiopolymer is at least 22 g/g and the AUL of the charge modifiedstarch-based biopolymer is at least 9 g/g at 0.7 psi in the salinesolution.
 9. The article of claim 1, wherein the biobased carbon contentof the charge modified starch-based biopolymer is at least approximately84%.
 10. The article of claim 1, wherein the SAP consists of the chargemodified starch-based biopolymer, wherein an absorption capacity of theabsorbent core is at least approximately 540 grams in the salinesolution.
 11. The article of claim 1, wherein the SAP consists of thecharge modified starch-based biopolymer, wherein a retention capacity ofthe absorbent core is at least approximately 333 grams in the salinesolution.
 12. The article of claim 1, wherein a ratio of SAP to fluff inthe absorbent core is between approximately 70% SAP to approximately 30%fluff and approximately 45% SAP to approximately 55% fluff.
 13. Anabsorbent sanitary article, comprising: a fluid-permeable top layer; afluid-resistant back layer; and an absorbent core; wherein the absorbentcore includes an absorbent fiber and a superabsorbent polymer (SAP);wherein the SAP is a modified biopolymer; wherein a biobased carboncontent of the modified biopolymer is at least approximately 84%;wherein the modified biopolymer has a Centrifuge Retention Capacity(CRC) of at least 17 g/g and an Absorbency Under Load (AUL) of at least7 g/g at 0.7 psi in a saline solution; and wherein the modifiedbiopolymer exhibits no cytotoxicity and is not a dermal irritant. 14.The article of claim 13, wherein the modified biopolymer is astarch-based biopolymer.
 15. The article of claim 13, wherein theprimary rewet under load of the absorbent core is less than about 3.0grams in saline, and wherein the secondary rewet under load of theabsorbent core is less than about 14 grams in saline.
 16. An absorbentsanitary article, comprising: a fluid-permeable top layer; afluid-resistant back layer; and an absorbent core; wherein the absorbentcore includes an absorbent fiber and a superabsorbent polymer (SAP);wherein a biobased carbon content of the SAP is at least approximately50%; wherein the SAP does not include a graft polymer or a non-biobasedpolymer; wherein the SAP has a Centrifuge Retention Capacity (CRC) of atleast 17 g/g and an Absorbency Under Load (AUL) of at least 7 g/g at 0.7psi in a saline solution; wherein the SAP consists of a starch-basedbiopolymer, wherein an absorption capacity of the absorbent core is atleast approximately 540 grams in the saline solution; and wherein thestarch-based biopolymer exhibits no cytotoxicity and is not a dermalirritant.
 17. The article of claim 16, wherein the starch-basedbiopolymer is crosslinked using at least two crosslinkers.
 18. Thearticle of claim 16, wherein the biobased carbon content of thestarch-based biopolymer is at least approximately 84%.
 19. The articleof claim 16, wherein the CRC of the starch-based biopolymer is at least22 g/g and the AUL of the starch-based biopolymer is at least 9 g/g at0.7 psi in the saline solution.
 20. An absorbent sanitary article,comprising: a fluid-permeable top layer; a fluid-resistant back layer;and an absorbent core; wherein the absorbent core includes an absorbentfiber and a superabsorbent polymer (SAP); wherein a biobased carboncontent of the SAP is at least approximately 50%; wherein the SAP doesnot include a graft polymer or a non-biobased polymer; wherein the SAPconsists of a starch-based biopolymer, wherein an absorption capacity ofthe absorbent core is at least approximately 540 grams in the salinesolution; and wherein a Centrifuge Retention Capacity (CRC) of thestarch-based biopolymer is at least 22 g/g and an Absorbency Under Load(AUL) of the starch-based biopolymer is at least 9 g/g at 0.7 psi in asaline solution.
 21. The article of claim 20, wherein the starch-basedbiopolymer is crosslinked using at least two crosslinkers.
 22. Thearticle of claim 20, wherein the biobased carbon content of thestarch-based biopolymer is at least approximately 84%.